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Radical expressions and rational exponents

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51430011
Evaluate each expression. a) \(\sqrt{\frac{144}{25}}\) b) \(\sqrt{2}\cdot\sqrt{18}\) c) \(\sqrt{0.0004}\) d) \(\sqrt{10^4}\)

Hints

- Use the product and quotient properties of square roots when appropriate. - Look for perfect squares in the numerator, denominator, or radicand. - Check a decimal square root by squaring your result.

Solution

1. \(\sqrt{\frac{144}{25}}=\frac{\sqrt{144}}{\sqrt{25}}=\frac{12}{5}=2.4\). 2. \(\sqrt{2}\cdot\sqrt{18}=\sqrt{36}=6\). 3. Since \(0.02^2=0.0004\), \(\sqrt{0.0004}=0.02\). 4. \(\sqrt{10^4}=\sqrt{10{,}000}=100\).

Answer

a) \(2.4\) b) \(6\) c) \(0.02\) d) \(100\)
51430211
Evaluate each square root without a calculator. First rewrite the mixed number as an improper fraction. a) \(\sqrt{1\frac{11}{25}}\) b) \(\sqrt{1\frac{13}{36}}\) c) \(\sqrt{1\frac{15}{49}}\) d) \(\sqrt{1\frac{19}{81}}\)

Hints

- Convert each mixed number to an improper fraction. - Use \(\sqrt{\frac{a}{b}}=\frac{\sqrt{a}}{\sqrt{b}}\) for positive \(a\) and \(b\). - Identify perfect squares in each numerator and denominator.

Solution

1. Rewrite the mixed numbers: \(1\frac{11}{25}=\frac{36}{25}\), \(1\frac{13}{36}=\frac{49}{36}\), \(1\frac{15}{49}=\frac{64}{49}\), and \(1\frac{19}{81}=\frac{100}{81}\). 2. For a), \(\sqrt{\frac{36}{25}}=\frac{6}{5}\). 3. For b), \(\sqrt{\frac{49}{36}}=\frac{7}{6}\). 4. For c), \(\sqrt{\frac{64}{49}}=\frac{8}{7}\). 5. For d), \(\sqrt{\frac{100}{81}}=\frac{10}{9}\).

Answer

a) \(\frac{6}{5}\) b) \(\frac{7}{6}\) c) \(\frac{8}{7}\) d) \(\frac{10}{9}\)
51435011
Evaluate each expression without a calculator. a) \(\sqrt{225}\cdot\sqrt{0.04}\) b) \(\frac{\sqrt{1000}}{\sqrt{10}}\) c) \(\sqrt{1\frac{7}{9}}\)

Hints

- Recognize perfect-square whole numbers and decimals. - Combine a quotient of square roots under one radical. - Convert the mixed number to an improper fraction.

Solution

1. \(\sqrt{225}\cdot\sqrt{0.04}=15\cdot0.2=3\). 2. \(\frac{\sqrt{1000}}{\sqrt{10}}=\sqrt{\frac{1000}{10}}=\sqrt{100}=10\). 3. Since \(1\frac{7}{9}=\frac{16}{9}\), \(\sqrt{1\frac{7}{9}}=\sqrt{\frac{16}{9}}=\frac{4}{3}\).

Answer

a) \(3\) b) \(10\) c) \(\frac{4}{3}\)
51435211
Evaluate each expression by simplifying strategically. a) \(\sqrt{17^2-15^2}\) b) \(\sqrt{5\sqrt{256}+1}\)

Hints

- Complete the operations inside the outer radical first. - Work from the innermost radical outward. - Look for a perfect-square final radicand.

Solution

1. For a), \(17^2-15^2=289-225=64\), so \(\sqrt{17^2-15^2}=\sqrt{64}=8\). 2. For b), begin with the inner radical: \(\sqrt{256}=16\). Then \(\sqrt{5\sqrt{256}+1}=\sqrt{5\cdot16+1}=\sqrt{81}=9\).

Answer

a) \(8\) b) \(9\)
51439711
Determine whether each result is rational or irrational. Justify your answer by simplifying the expression. a) \(\sqrt{8}\sqrt{2}\) b) \(\sqrt{3} + \sqrt{27}\) c) \((5-\sqrt{6})(5+\sqrt{6})\)

Hints

- Use radical properties to combine or simplify products. - Look for perfect-square factors in larger radicands. - Part c) has the structure of a difference of squares. - What happens when a square root is squared?

Solution

1. \(\sqrt{8}\sqrt{2} = \sqrt{16} = 4\), so the result is rational. 2. \(\sqrt{27} = \sqrt{9 \cdot 3} = 3\sqrt{3}\). Therefore, \(\sqrt{3} + \sqrt{27} = 4\sqrt{3}\), which is irrational. 3. Using the difference of squares, \((5-\sqrt{6})(5+\sqrt{6}) = 5^2 - (\sqrt{6})^2 = 25-6 = 19\), so the result is rational.

Answer

a) Rational: \(4\) b) Irrational: \(4\sqrt{3}\) c) Rational: \(19\)
51441011
Simplify each expression completely without a calculator. a) \(\sqrt{3}\cdot\sqrt{27}\) b) \(\frac{\sqrt{72}}{\sqrt{2}}\) c) \(\sqrt{400}-\sqrt{144}\)

Hints

- Combine products or quotients of square roots when possible. - For a difference, evaluate each square root separately.

Solution

1. \(\sqrt{3}\cdot\sqrt{27}=\sqrt{81}=9\). 2. \(\frac{\sqrt{72}}{\sqrt{2}}=\sqrt{36}=6\). 3. \(\sqrt{400}-\sqrt{144}=20-12=8\).

Answer

a) \(9\) b) \(6\) c) \(8\)
51441911
Simplify each radical expression without a calculator. State the conditions on the variables that make the original expression real and defined. a) \(\sqrt{7}\cdot\sqrt{28}\) b) \(\frac{\sqrt{45x^3}}{\sqrt{5x}}\) c) \(2\sqrt{a}\cdot3\sqrt{a}\) d) \(\sqrt{12}+\sqrt{48}\)

Hints

- Combine products or quotients of square roots when their domains permit it. - A radical in a denominator must be defined and nonzero. - Simplify \(\sqrt{x^2}\) using the known sign of \(x\). - A square root multiplied by itself returns the radicand when defined.

Solution

1. \(\sqrt{7}\sqrt{28}=\sqrt{196}=14\). No variable restriction is needed. 2. The denominator requires \(x>0\). Then \(\frac{\sqrt{45x^3}}{\sqrt{5x}}=\sqrt{9x^2}=3x\). 3. The radicals require \(a\ge0\). Then \(2\sqrt{a}\cdot3\sqrt{a}=6a\). 4. \(\sqrt{12}+\sqrt{48}=2\sqrt{3}+4\sqrt{3}=6\sqrt{3}\). No variable restriction is needed.

Answer

a) \(14\) b) \(3x\), for \(x>0\) c) \(6a\), for \(a\ge0\) d) \(6\sqrt{3}\)
51442511
Write each expression as a single square root by moving the nonnegative factor inside the radical. a) \(4\sqrt{5}\) b) \(\frac{2}{3}\sqrt{18}\) c) \(0.2\sqrt{200}\) d) \(k\sqrt{k}\), for \(k\ge0\)

Hints

- Square the outside factor when moving it under the radical. - Square both numerator and denominator of a fractional coefficient. - Reverse the usual extraction rule by moving a factor under the radical. - The nonnegative condition ensures the transformation preserves the value.

Solution

1. Use \(c\sqrt{d}=\sqrt{c^2d}\) for \(c\ge0\). 2. \(4\sqrt{5}=\sqrt{16\cdot5}=\sqrt{80}\). 3. \(\frac{2}{3}\sqrt{18}=\sqrt{\frac{4}{9}\cdot18}=\sqrt{8}\). 4. \(0.2\sqrt{200}=\sqrt{0.04\cdot200}=\sqrt{8}\). 5. \(k\sqrt{k}=\sqrt{k^2\cdot k}=\sqrt{k^3}\).

Answer

a) \(\sqrt{80}\) b) \(\sqrt{8}\) c) \(\sqrt{8}\) d) \(\sqrt{k^3}\)
51443711
For \(r,s,y\ge0\) and \(x\in\mathbb{R}\), expand each expression using a binomial formula and simplify. a) \((\sqrt{r}+4)^2\) b) \((5-\sqrt{s})^2\) c) \((\sqrt{3}x+\sqrt{2})^2\) d) \(\left(\frac{\sqrt{y}}{3}-6\right)^2\)

Hints

- Match each expression to a square-of-a-sum or square-of-a-difference formula. - Use \((\sqrt{u})^2=u\) for nonnegative \(u\). - Square every factor in a product. - Combine radical factors in the middle term.

Solution

1. \((\sqrt{r}+4)^2=r+8\sqrt{r}+16\). 2. \((5-\sqrt{s})^2=25-10\sqrt{s}+s\). 3. \((\sqrt{3}x+\sqrt{2})^2=3x^2+2\sqrt{6}x+2\). 4. \(\left(\frac{\sqrt{y}}{3}-6\right)^2=\frac{y}{9}-4\sqrt{y}+36\).

Answer

a) \(r+8\sqrt{r}+16\) b) \(25-10\sqrt{s}+s\) c) \(3x^2+2\sqrt{6}x+2\) d) \(\frac{y}{9}-4\sqrt{y}+36\)
51444311
Simplify each radical by rewriting its radicand as a perfect square. a) \(\sqrt{x^2+6x+9}\) b) \(\sqrt{y^2-10y+25}\) c) \(\sqrt{16+8a+a^2}\) d) \(\sqrt{b^2-2b+1}\)

Hints

- Match each trinomial to a squared-binomial pattern. - Identify which terms are the squares of the two binomial terms. - Check whether the middle term is twice the product of the binomial terms. - Remember that \(\sqrt{u^2}=|u|\).

Solution

1. In a), \(x^2+6x+9=(x+3)^2\), so the result is \(|x+3|\). 2. In b), \(y^2-10y+25=(y-5)^2\), so the result is \(|y-5|\). 3. In c), \(16+8a+a^2=(a+4)^2\), so the result is \(|a+4|\). 4. In d), \(b^2-2b+1=(b-1)^2\), so the result is \(|b-1|\).

Answer

a) \(|x+3|\) b) \(|y-5|\) c) \(|a+4|\) d) \(|b-1|\)
51446711
For \(x\ge0\) and \(y\ge0\), simplify completely: \(4x\sqrt{y}-\sqrt{9x^2y}+2x\sqrt{y}\)

Hints

- Rewrite the middle radical as a term like the other two. - Extract the perfect-square factors \(9\) and \(x^2\). - Combine like radical terms.

Solution

1. Since \(x\ge0\), \(\sqrt{9x^2y}=3x\sqrt{y}\). 2. Therefore, \(4x\sqrt{y}-3x\sqrt{y}+2x\sqrt{y}=3x\sqrt{y}\).

Answer

\(3x\sqrt{y}\)
51446911
For \(p\ge0\) and \(q\ge0\), simplify completely: \((\sqrt{2p}+\sqrt{3q})(\sqrt{2p}-\sqrt{3q})+3q-p\)

Hints

- Recognize the product of conjugates. - Square each radical term. - Combine the remaining like terms.

Solution

1. Use the difference of squares: \((\sqrt{2p}+\sqrt{3q})(\sqrt{2p}-\sqrt{3q})=2p-3q\). 2. Then \(2p-3q+3q-p=p\).

Answer

\(p\)
51447011
Find all real numbers \(x\) for which \(\sqrt{24-4x}\) is defined.

Hints

- A real square root requires a nonnegative radicand. - Reverse the inequality when dividing by a negative number. - Test a value on each side of the boundary.

Solution

1. The radicand must be nonnegative: \(24-4x\ge0\). 2. Solving the inequality gives \(-4x\ge-24\), so \(x\le6\).

Answer

\(x\le6\)
51496811
Simplify each expression as far as possible. Assume \(x>0\) and \(a>0\). a) \(\sqrt3\sqrt{12}\) b) \(\frac{\sqrt{x^3}}{\sqrt{x}}\) c) \(\sqrt[3]{2}\sqrt[3]{4}\) d) \(\sqrt{a}\sqrt[4]{a}\)

Hints

- Combine radicals with the same index. - Rewrite radicals as rational exponents when the indices differ. - Use the positivity assumptions when simplifying an even root.

Solution

1. \(\sqrt3\sqrt{12}=\sqrt{36}=6\). 2. \(\frac{\sqrt{x^3}}{\sqrt{x}}=\sqrt{x^2}=x\), since \(x>0\). 3. \(\sqrt[3]{2}\sqrt[3]{4}=\sqrt[3]{8}=2\). 4. \(\sqrt{a}\sqrt[4]{a}=a^{\frac12}a^{\frac14}=a^{\frac34}=\sqrt[4]{a^3}\).

Answer

a) \(6\) b) \(x\) c) \(2\) d) \(\sqrt[4]{a^3}\)
51541511
Simplify \(\frac{\sqrt[4]{b^9}\sqrt[4]{b^3}}{\sqrt[4]{b^4}}\) as far as possible. Assume \(b>0\).

Hints

- Combine the fourth roots in the numerator. - Use the quotient property for radicals with the same index. - Rewrite the final radical as a rational exponent.

Solution

1. Combine the fourth roots: \(\frac{\sqrt[4]{b^9}\sqrt[4]{b^3}}{\sqrt[4]{b^4}}=\sqrt[4]{\frac{b^{12}}{b^4}}\). 2. Simplify the radicand: \(\sqrt[4]{b^8}=b^2\), since \(b>0\).

Answer

\(b^2\)
51548811
Evaluate or simplify each expression. a) \(\sqrt{13^2-12^2}\) b) \(\sqrt{72}\) c) \(\sqrt{\frac{25}{81}}\)

Hints

- Complete operations inside a radical before taking the square root. - Factor out the greatest perfect-square factor. - Apply the quotient property to a square root of a fraction.

Solution

1. \(\sqrt{13^2-12^2}=\sqrt{169-144}=\sqrt{25}=5\). 2. \(\sqrt{72}=\sqrt{36\cdot2}=6\sqrt{2}\). 3. \(\sqrt{\frac{25}{81}}=\frac{\sqrt{25}}{\sqrt{81}}=\frac{5}{9}\).

Answer

a) \(5\) b) \(6\sqrt{2}\) c) \(\frac{5}{9}\)
51552311
For \(z\ge0\), simplify completely: \(\sqrt{225z^4-81z^4}\)

Hints

- Combine like terms inside the radical first. - Factor the radicand as a product of perfect squares. - Take the square root of the coefficient and halve the even exponent.

Solution

1. Combine like terms inside the radical: \(225z^4-81z^4=144z^4\). 2. Then \(\sqrt{144z^4}=12z^2\).

Answer

\(12z^2\)
51555111
Simplify each expression. State the values of the variable for which the expression is defined. a) \(2\sqrt{a}+5\sqrt{a}-\sqrt{a}\) b) \(x\sqrt{3}-0.5x\sqrt{3}\) c) \(\sqrt{25z^2}+\sqrt{z^2}\)

Hints

- Identify radical terms with the same radicand. - A variable directly under a square root must make the radicand nonnegative. - Recall how \(\sqrt{u^2}\) is related to \(u\).

Solution

1. In a), combine the coefficients of the like radical terms: \((2+5-1)\sqrt{a}=6\sqrt{a}\). The radicand requires \(a\ge0\). 2. In b), factor out \(x\sqrt{3}\): \((1-0.5)x\sqrt{3}=0.5x\sqrt{3}\). The expression is defined for every real \(x\). 3. In c), \(\sqrt{25z^2}=5|z|\) and \(\sqrt{z^2}=|z|\). Therefore, the expression simplifies to \(6|z|\) and is defined for every real \(z\).

Answer

a) \(6\sqrt{a}\), for \(a\ge0\) b) \(0.5x\sqrt{3}\), for \(x\in\mathbb{R}\) c) \(6|z|\), for \(z\in\mathbb{R}\)
51555911
Evaluate without a calculator. \(\sqrt2\sqrt{32}-\sqrt[3]{27}+\frac{\sqrt{50}}{\sqrt2}\)

Hints

- Combine square roots in each product or quotient. - Evaluate the cube root separately. - Add and subtract only after simplifying each part.

Solution

1. \(\sqrt2\sqrt{32}=\sqrt{64}=8\). 2. \(\sqrt[3]{27}=3\). 3. \(\frac{\sqrt{50}}{\sqrt2}=\sqrt{25}=5\). 4. Therefore, \(8-3+5=10\).

Answer

\(10\)
52465711
Find the maximal real domain of each function. 1) \(f(x)=\sqrt[4]{5x-20}\) 2) \(g(x)=\sqrt[5]{x+12}\) 3) \(h(x)=\sqrt[6]{18-3x}\) 4) \(k(x)=\sqrt{x^2+9}\)

Hints

- For an even-index radical, require the radicand to be nonnegative. - An odd-index radical accepts every real radicand. - Solve each resulting inequality for \(x\).

Solution

1. An even root requires \(5x-20\geq0\). Thus \(x\geq4\), so the domain is \([4,\infty)\). 2. A fifth root is defined for every real radicand, so the domain is \((-\infty, \infty)\). 3. An even root requires \(18-3x\geq0\). Thus \(x\leq6\), so the domain is \((-\infty, 6]\). 4. Since \(x^2+9>0\) for every real \(x\), the domain is \((-\infty, \infty)\).

Answer

1) \([4,\infty)\) 2) \((-\infty, \infty)\) 3) \((-\infty, 6]\) 4) \((-\infty, \infty)\)
52466511
Simplify each expression under the stated condition. a) \(\sqrt{(a-7)^2}\), for \(a<7\) b) \(\sqrt{(2x-6)^2}\), for \(x>3\) Briefly explain why the result in part a is positive for every allowed value of \(a\).

Hints

- First rewrite each square root of a square as an absolute value. - Use the given inequality to determine the sign inside the absolute value. - A principal square root is always nonnegative. - Think of absolute value as the nonnegative distance from zero.

Solution

1. In a), \(\sqrt{(a-7)^2}=|a-7|\). Since \(a<7\), \(a-7<0\), so \(|a-7|=7-a\). 2. In b), \(\sqrt{(2x-6)^2}=|2x-6|\). Since \(x>3\), \(2x-6>0\), so the result is \(2x-6\). 3. For every \(a<7\), \(7-a>0\). This agrees with the fact that a principal square root is nonnegative.

Answer

a) \(7-a\) b) \(2x-6\) In part a, \(7-a>0\) because \(a<7\).
52468911
For the stated variable conditions, extract every possible factor from each radical. 1) \(\sqrt{(x-7)^5}\), for \(x\ge7\) 2) \(\sqrt{a^3(b+2)^2}\), for \(a\ge0\) and \(b\ge-2\)

Hints

- Factor each radicand into perfect-square factors and any factor left over. - Use the stated conditions to determine the signs of expressions inside absolute values. - Apply the product property of square roots only to nonnegative factors.

Solution

1. Rewrite the radicand as \((x-7)^4(x-7)\). Since \(x-7\ge0\), \(\sqrt{(x-7)^4}=(x-7)^2\). Thus, the expression is \((x-7)^2\sqrt{x-7}\). 2. Rewrite the radicand as \(a^2\cdot a\cdot(b+2)^2\). Since \(a\ge0\) and \(b+2\ge0\), \(\sqrt{a^2}=a\) and \(\sqrt{(b+2)^2}=b+2\). Thus, the expression is \(a(b+2)\sqrt{a}\).

Answer

1) \((x-7)^2\sqrt{x-7}\) 2) \(a(b+2)\sqrt{a}\)
52470911
Simplify each expression by extracting perfect-power factors. State its real domain. 1) \(\sqrt{a^5}\) 2) \(\sqrt[3]{(x-2)^4}\) 3) \(\sqrt[5]{(y+3)^5}\)

Hints

- An even-index radical requires a nonnegative radicand. - Split a power into a factor whose exponent matches the radical index and a remainder. - Odd-index radicals are defined for every real radicand.

Solution

1. The square root requires \(a^5\geq0\), so \(a\geq0\). Then \(\sqrt{a^5}=\sqrt{a^4a}=a^2\sqrt{a}\). 2. A cube root is defined for every real \(x\). Also, \(\sqrt[3]{(x-2)^4}=(x-2)\sqrt[3]{x-2}\). 3. A fifth root is defined for every real \(y\), and \(\sqrt[5]{(y+3)^5}=y+3\).

Answer

1) \(a^2\sqrt{a}\), for \(a\geq0\) 2) \((x-2)\sqrt[3]{x-2}\), for \(x\in\mathbb R\) 3) \(y+3\), for \(y\in\mathbb R\)
52472111
Compare each pair by moving the coefficient inside the radical. Which expression is greater? a) \(3\sqrt7\) and \(5\sqrt3\) b) \(2\sqrt[3]{5}\) and \(3\sqrt[3]{2}\) c) Show algebraically that \(a^2\sqrt a=\sqrt{a^5}\) for \(a\geq0\).

Hints

- Raise an outside coefficient to the radical index before moving it inside. - Once the radical indices match, compare the radicands. - Use the condition \(a\geq0\) in part c.

Solution

1. \(3\sqrt7=\sqrt{3^2\cdot7}=\sqrt{63}\), while \(5\sqrt3=\sqrt{5^2\cdot3}=\sqrt{75}\). Since \(75>63\), \(5\sqrt3>3\sqrt7\). 2. \(2\sqrt[3]{5}=\sqrt[3]{2^3\cdot5}=\sqrt[3]{40}\), while \(3\sqrt[3]{2}=\sqrt[3]{3^3\cdot2}=\sqrt[3]{54}\). Since \(54>40\), \(3\sqrt[3]{2}>2\sqrt[3]{5}\). 3. Since \(a\geq0\), \(a^2\sqrt a=\sqrt{(a^2)^2}\sqrt a=\sqrt{a^4a}=\sqrt{a^5}\).

Answer

a) \(5\sqrt3>3\sqrt7\) b) \(3\sqrt[3]{2}>2\sqrt[3]{5}\) c) \(a^2\sqrt a=\sqrt{a^5}\)
52472311
Rewrite each expression so that every factor is inside one radical. Simplify the radicand. Assume all variables are positive. a) \(4a\sqrt{3a}\) b) \(\frac{x}{y}\sqrt[3]{\frac{y^4}{x^2}}\) c) \(b^2\sqrt[5]{\frac2{b^7}}\)

Hints

- Raise each outside factor to the radical index before moving it inside. - Simplify products and quotients of powers after combining them. - Use the positivity assumptions to preserve equivalence.

Solution

1. \(4a\sqrt{3a}=\sqrt{(4a)^2\cdot3a}=\sqrt{48a^3}\). 2. \(\frac{x}{y}\sqrt[3]{\frac{y^4}{x^2}}=\sqrt[3]{\left(\frac{x}{y}\right)^3\frac{y^4}{x^2}}=\sqrt[3]{xy}\). 3. \(b^2\sqrt[5]{\frac2{b^7}}=\sqrt[5]{(b^2)^5\frac2{b^7}}=\sqrt[5]{2b^3}\).

Answer

a) \(\sqrt{48a^3}\) b) \(\sqrt[3]{xy}\) c) \(\sqrt[5]{2b^3}\)
52473111
Write each expression as a single radical. Assume \(a\), \(b\), \(x\), and \(y\) are positive real numbers, \(n\geq2\) is a natural number, and \(k\) is a natural number. 1) \(a^3\sqrt[5]{a^2}\) 2) \(xy^2\sqrt[n]{x^2y}\) 3) \(b^k\sqrt[3]{b}\)

Hints

- Raise each outside factor to the radical index before moving it inside. - Use \((u^p)^q=u^{pq}\). - Add exponents when multiplying powers with the same base.

Solution

1. \(a^3\sqrt[5]{a^2}=\sqrt[5]{(a^3)^5a^2}=\sqrt[5]{a^{17}}\). 2. \(xy^2\sqrt[n]{x^2y}=\sqrt[n]{x^ny^{2n}x^2y}=\sqrt[n]{x^{n+2}y^{2n+1}}\). 3. \(b^k\sqrt[3]{b}=\sqrt[3]{(b^k)^3b}=\sqrt[3]{b^{3k+1}}\).

Answer

1) \(\sqrt[5]{a^{17}}\) 2) \(\sqrt[n]{x^{n+2}y^{2n+1}}\) 3) \(\sqrt[3]{b^{3k+1}}\)
52474311
Rewrite each expression so that no fraction remains inside the radical. Simplify as far as possible. a) \(\sqrt{\frac35}\) b) \(\sqrt[3]{\frac29}\) c) \(\sqrt[4]{\frac18}\) d) \(\sqrt[n]{\frac13}\), where \(n\geq2\) is a natural number

Hints

- Multiply the numerator and denominator so the denominator becomes a perfect power matching the radical index. - Then split the radical of the quotient. - For part d, determine the power of \(3\) needed to make \(3^n\).

Solution

1. \(\sqrt{\frac35}=\sqrt{\frac{15}{25}}=\frac{\sqrt{15}}5\). 2. \(\sqrt[3]{\frac29}=\sqrt[3]{\frac6{27}}=\frac{\sqrt[3]{6}}3\). 3. \(\sqrt[4]{\frac18}=\sqrt[4]{\frac2{16}}=\frac{\sqrt[4]{2}}2\). 4. \(\sqrt[n]{\frac13}=\sqrt[n]{\frac{3^{n-1}}{3^n}}=\frac{\sqrt[n]{3^{n-1}}}{3}\).

Answer

a) \(\frac{\sqrt{15}}5\) b) \(\frac{\sqrt[3]{6}}3\) c) \(\frac{\sqrt[4]{2}}2\) d) \(\frac{\sqrt[n]{3^{n-1}}}{3}\)
52476311
Simplify each expression completely. Assume all variables are positive. a) \(6x\sqrt{\frac{y}{3x}}\) b) \(\frac{a}{2}\sqrt{\frac{20b}{a}}\)

Hints

- A positive factor moved under a square root must be squared. - Simplify fractions and variable powers inside the radical. - Check whether the final radicand contains a perfect-square factor.

Solution

1. In a), move the positive factor \(6x\) under the radical by squaring it: \(6x\sqrt{\frac{y}{3x}}=\sqrt{(6x)^2\cdot\frac{y}{3x}}=\sqrt{12xy}\). 2. Extract the perfect-square factor \(4\): \(\sqrt{12xy}=2\sqrt{3xy}\). 3. In b), move \(\frac{a}{2}\) under the radical: \(\frac{a}{2}\sqrt{\frac{20b}{a}}=\sqrt{\left(\frac{a}{2}\right)^2\cdot\frac{20b}{a}}=\sqrt{5ab}\).

Answer

a) \(2\sqrt{3xy}\) b) \(\sqrt{5ab}\)
52476711
Simplify each radical by extracting perfect-power factors. Assume all variables are positive real numbers. 1) \(\sqrt{75x^5y^2}\) 2) \(\sqrt[3]{\frac{8a^4}{27b^3}}\)

Hints

- Factor each radicand into a perfect power and a remaining factor. - Match the perfect power to the radical index. - Use the positivity assumptions when extracting variable factors.

Solution

1. \(\sqrt{75x^5y^2}=\sqrt{25x^4y^2\cdot3x}=5x^2y\sqrt{3x}\). 2. \(\sqrt[3]{\frac{8a^4}{27b^3}}=\sqrt[3]{\frac{2^3a^3a}{3^3b^3}}=\frac{2a}{3b}\sqrt[3]{a}\).

Answer

1) \(5x^2y\sqrt{3x}\) 2) \(\frac{2a}{3b}\sqrt[3]{a}\)
52479611
Almost every expression in the list is a rational multiple of \(\sqrt{7}\). Such expressions are like radicals with \(\sqrt{7}\). Which expression does not belong? Justify your answer by simplifying every expression. \(\sqrt{112},\ \sqrt{175},\ \sqrt{252},\ \sqrt{\frac{7}{16}},\ \sqrt{70}\)

Hints

- Factor perfect squares from each radicand. - A like radical must simplify to \(k\sqrt{7}\) for rational \(k\). - Test the quotient of each expression and \(\sqrt{7}\).

Solution

1. \(\sqrt{112}=\sqrt{16\cdot7}=4\sqrt{7}\). 2. \(\sqrt{175}=\sqrt{25\cdot7}=5\sqrt{7}\). 3. \(\sqrt{252}=\sqrt{36\cdot7}=6\sqrt{7}\). 4. \(\sqrt{\frac{7}{16}}=\frac{\sqrt{7}}{4}\). 5. For \(\sqrt{70}\), the quotient \(\frac{\sqrt{70}}{\sqrt{7}}=\sqrt{10}\) is irrational, so \(\sqrt{70}\) is not a rational multiple of \(\sqrt{7}\).

Answer

\(\sqrt{70}\) does not belong. The other four expressions are rational multiples of \(\sqrt{7}\).
52482311
Determine whether each pair consists of like radical terms. Like radical terms can be simplified to expressions with the same index and the same radicand. Assume the variables make all expressions defined. a) \(\sqrt{20x^3}\) and \(\sqrt{45x}\) b) \(\sqrt{a^2+b^2}\) and \(\sqrt{a^2-b^2}\) c) \(\sqrt{\frac{1}{3y}}\) and \(\sqrt{3y}\)

Hints

- Simplify each radical before comparing the pair. - A sum or difference inside a radical cannot generally be separated. - For the reciprocal radical, rationalize the denominator and compare the resulting radicand. - Look for perfect-square factors before deciding whether two radicals are like.

Solution

1. In a), \(\sqrt{20x^3}=2x\sqrt{5x}\) and \(\sqrt{45x}=3\sqrt{5x}\). Both simplified terms have radicand \(5x\), so they are like radical terms. 2. In b), neither radicand can be simplified, and \(a^2+b^2\) and \(a^2-b^2\) are different. The terms are not like radical terms. 3. In c), \(\sqrt{\frac{1}{3y}}=\frac{1}{\sqrt{3y}}=\frac{\sqrt{3y}}{3y}\). Both expressions can therefore be written as coefficients times \(\sqrt{3y}\), so they are like radical terms.

Answer

a) Like radical terms b) Not like radical terms c) Like radical terms
52483111
For \(b\ge0\), simplify completely: \(3\sqrt{49b}-2(\sqrt{100b}-4\sqrt{b})\)

Hints

- Extract the perfect-square factors \(49\) and \(100\). - Simplify inside the parentheses before distributing the outside factor. - Combine the resulting like radical terms.

Solution

1. Simplify the radicals: \(\sqrt{49b}=7\sqrt{b}\) and \(\sqrt{100b}=10\sqrt{b}\). 2. Substitute and simplify inside the parentheses: \(3\cdot7\sqrt{b}-2(10\sqrt{b}-4\sqrt{b})=21\sqrt{b}-2(6\sqrt{b})\). 3. Combine like radical terms: \(21\sqrt{b}-12\sqrt{b}=9\sqrt{b}\).

Answer

\(9\sqrt{b}\)
52483511
Simplify by extracting perfect cubes and combining like radical terms. \(2\sqrt[3]{16}+\sqrt[3]{54}-\sqrt[3]{250}+\sqrt[3]{128}\)

Hints

- Factor each radicand into a perfect cube times \(2\). - Extract the cube root of the perfect cube. - Combine the coefficients of the common radical part.

Solution

1. \(2\sqrt[3]{16}=2\sqrt[3]{8\cdot2}=4\sqrt[3]{2}\). 2. \(\sqrt[3]{54}=3\sqrt[3]{2}\), \(\sqrt[3]{250}=5\sqrt[3]{2}\), and \(\sqrt[3]{128}=4\sqrt[3]{2}\). 3. Combine coefficients: \((4+3-5+4)\sqrt[3]{2}=6\sqrt[3]{2}\).

Answer

\(6\sqrt[3]{2}\)
52483711
Simplify completely: \((2\sqrt{18}+\sqrt{12})+(\sqrt{8}-3\sqrt{27})\)

Hints

- Extract perfect-square factors from each radicand. - Combine only terms with identical radicands. - Keep track of each sign when removing parentheses.

Solution

1. Rewrite each radical: \(2\sqrt{18}=6\sqrt{2}\), \(\sqrt{12}=2\sqrt{3}\), \(\sqrt{8}=2\sqrt{2}\), and \(3\sqrt{27}=9\sqrt{3}\). 2. Combine like radicals: \((6\sqrt{2}+2\sqrt{3})+(2\sqrt{2}-9\sqrt{3})=8\sqrt{2}-7\sqrt{3}\).

Answer

\(8\sqrt{2}-7\sqrt{3}\)
52485011
Simplify each expression completely. a) \((3\sqrt{5}+2\sqrt{2})(3\sqrt{5}-2\sqrt{2})\) b) \(\left(\frac{1}{3}\sqrt{a}-\sqrt{b}\right)\left(\frac{1}{3}\sqrt{a}+\sqrt{b}\right)\), for \(a,b\ge0\) c) \(\sqrt{(\sqrt{13}-2)(\sqrt{13}+2)}\)

Hints

- Each product has the form \((u+v)(u-v)\). - When squaring a coefficient times a radical, square both factors. - In c), simplify the product inside the outer radical first.

Solution

1. In a), use the difference of squares: \((3\sqrt{5})^2-(2\sqrt{2})^2=45-8=37\). 2. In b), use the same identity: \(\left(\frac{1}{3}\sqrt{a}\right)^2-(\sqrt{b})^2=\frac{a}{9}-b\). 3. In c), first simplify the product under the outer radical: \((\sqrt{13}-2)(\sqrt{13}+2)=13-4=9\). Then \(\sqrt{9}=3\).

Answer

a) \(37\) b) \(\frac{a}{9}-b\) c) \(3\)
52487311
Simplify each expression. Write any remaining fractional power in radical form. Assume all variables are positive. 1) \(\frac{\sqrt[4]{x^5}}{\sqrt[4]{x}}\) 2) \(\sqrt[3]{a}\sqrt[6]{a}\) 3) \(\frac{\sqrt{y^3}}{\sqrt[4]{y}}\)

Hints

- Combine radicals with the same index directly. - Rewrite different radical indices as rational exponents. - Add exponents when multiplying and subtract them when dividing.

Solution

1. \(\frac{\sqrt[4]{x^5}}{\sqrt[4]{x}}=\sqrt[4]{x^4}=x\). 2. \(\sqrt[3]{a}\sqrt[6]{a}=a^{\frac13+\frac16}=a^{\frac12}=\sqrt a\). 3. \(\frac{\sqrt{y^3}}{\sqrt[4]{y}}=y^{\frac32-\frac14}=y^{\frac54}=y\sqrt[4]{y}\).

Answer

1) \(x\) 2) \(\sqrt a\) 3) \(y\sqrt[4]{y}\)
52487511
Two squares have areas \(A_1=162\,\text{m}^2\) and \(A_2=2\,\text{m}^2\). a) Find the ratio of their side lengths \(a_1:a_2\). b) How does the ratio change if both areas are doubled? Briefly justify your answer.

Hints

- A square's side length is the square root of its area. - Combine the quotient of square roots under one radical. - A common scale factor in both areas cancels in the ratio.

Solution

1. The side-length ratio is \(\frac{a_1}{a_2}=\frac{\sqrt{162}}{\sqrt{2}}=\sqrt{81}=9\), so \(a_1:a_2=9:1\). 2. After doubling both areas, the ratio is \(\frac{\sqrt{2A_1}}{\sqrt{2A_2}}=\sqrt{\frac{A_1}{A_2}}\). The common factor \(2\) cancels, so the ratio remains \(9:1\).

Answer

a) \(9:1\) b) The ratio remains \(9:1\).
52487611
Evaluate and simplify each quotient. a) \(\frac{\sqrt{180}}{\sqrt{5}}\) b) \(\frac{\sqrt{1.2}}{\sqrt{0.3}}\) c) \(\frac{\sqrt{5}\cdot\sqrt{20}}{\sqrt{4}}\) d) \(\frac{\sqrt{27a^3}}{\sqrt{3a}}\), for \(a>0\)

Hints

- Use the quotient property to combine two square roots into one. - Simplify the quotient inside the radical before taking the square root. - In d), apply the quotient rule for powers with the same base. - Use the stated sign condition when simplifying \(\sqrt{a^2}\).

Solution

1. In a), \(\frac{\sqrt{180}}{\sqrt{5}}=\sqrt{\frac{180}{5}}=\sqrt{36}=6\). 2. In b), \(\frac{\sqrt{1.2}}{\sqrt{0.3}}=\sqrt{\frac{1.2}{0.3}}=\sqrt{4}=2\). 3. In c), combine the radicals: \(\frac{\sqrt{5\cdot20}}{\sqrt{4}}=\sqrt{\frac{100}{4}}=\sqrt{25}=5\). 4. In d), \(\frac{\sqrt{27a^3}}{\sqrt{3a}}=\sqrt{\frac{27a^3}{3a}}=\sqrt{9a^2}=3a\), because \(a>0\).

Answer

a) \(6\) b) \(2\) c) \(5\) d) \(3a\)
52487711
Simplify each expression completely. Assume all variables are positive. 1) \(\frac{\sqrt{108}}{\sqrt{3}}\) 2) \(\frac{\sqrt{125x^3}}{\sqrt{5x}}\) 3) \(\frac{12\sqrt{10}}{3\sqrt{2}}\)

Hints

- Combine a quotient of square roots under one radical. - Simplify the numerical and variable factors inside the radical. - Divide coefficients outside the radicals separately. - Check whether the final radicand contains a perfect-square factor.

Solution

1. \(\frac{\sqrt{108}}{\sqrt{3}}=\sqrt{\frac{108}{3}}=\sqrt{36}=6\). 2. \(\frac{\sqrt{125x^3}}{\sqrt{5x}}=\sqrt{\frac{125x^3}{5x}}=\sqrt{25x^2}=5x\). 3. Divide the coefficients and combine the radicals: \(\frac{12\sqrt{10}}{3\sqrt{2}}=4\sqrt{\frac{10}{2}}=4\sqrt{5}\).

Answer

1) \(6\) 2) \(5x\) 3) \(4\sqrt{5}\)
52488111
Factor each sum or difference by extracting a common radical factor. 1) \(\sqrt{15}+\sqrt{10}\) 2) \(\sqrt{21}-\sqrt{14}\) 3) \(\sqrt{33}+\sqrt{22}\) 4) \(\sqrt{26}-\sqrt{13}\)

Hints

- Rewrite each radicand as a product with a common factor. - Apply the distributive property in reverse. - In part 4), write \(\sqrt{13}=\sqrt{13}\cdot1\).

Solution

1. \(\sqrt{15}+\sqrt{10}=\sqrt{5}\sqrt{3}+\sqrt{5}\sqrt{2}=\sqrt{5}(\sqrt{3}+\sqrt{2})\). 2. \(\sqrt{21}-\sqrt{14}=\sqrt{7}(\sqrt{3}-\sqrt{2})\). 3. \(\sqrt{33}+\sqrt{22}=\sqrt{11}(\sqrt{3}+\sqrt{2})\). 4. \(\sqrt{26}-\sqrt{13}=\sqrt{13}(\sqrt{2}-1)\).

Answer

1) \(\sqrt{5}(\sqrt{3}+\sqrt{2})\) 2) \(\sqrt{7}(\sqrt{3}-\sqrt{2})\) 3) \(\sqrt{11}(\sqrt{3}+\sqrt{2})\) 4) \(\sqrt{13}(\sqrt{2}-1)\)
52488511
Simplify each expression completely. Assume all variables are positive. 1) \(\frac{\sqrt{20x^3y}+\sqrt{5xy^3}}{\sqrt{5xy}}\) 2) \(\frac{\sqrt{a}-\sqrt{4a}}{\sqrt{a}}\)

Hints

- Distribute division across the terms in each numerator. - Use the quotient property to combine each quotient of radicals. - Simplify the fractions inside the radicals before taking square roots. - Notice that \(\sqrt{4a}=2\sqrt{a}\).

Solution

1. Divide each term in the numerator by \(\sqrt{5xy}\): \(\sqrt{\frac{20x^3y}{5xy}}+\sqrt{\frac{5xy^3}{5xy}}=\sqrt{4x^2}+\sqrt{y^2}\). 2. Because the variables are positive, \(\sqrt{4x^2}=2x\) and \(\sqrt{y^2}=y\). The result is \(2x+y\). 3. For 2), divide each numerator term by \(\sqrt{a}\): \(\frac{\sqrt{a}}{\sqrt{a}}-\frac{\sqrt{4a}}{\sqrt{a}}=1-\sqrt{4}=-1\).

Answer

1) \(2x+y\) 2) \(-1\)
52488911
Factor each expression by taking out the greatest common factor. Assume all variable values make the expressions defined. 1) \(\sqrt{5a}+\sqrt{15a}\) 2) \(b-\sqrt b\) 3) \(\sqrt[3]{x^2y}+\sqrt[3]{xy^2}\)

Hints

- Split radicands to reveal a common radical factor. - Rewrite an unrooted variable as a product involving its square root when useful. - Factor just as you would with ordinary algebraic terms.

Solution

1. Since \(\sqrt{15a}=\sqrt{5a}\sqrt3\), the expression factors as \(\sqrt{5a}(1+\sqrt3)\). 2. Write \(b=\sqrt b\sqrt b\). Then \(b-\sqrt b=\sqrt b(\sqrt b-1)\). 3. Each term contains \(\sqrt[3]{xy}\): \(\sqrt[3]{x^2y}+\sqrt[3]{xy^2}=\sqrt[3]{xy}(\sqrt[3]{x}+\sqrt[3]{y})\).

Answer

1) \(\sqrt{5a}(1+\sqrt3)\) 2) \(\sqrt b(\sqrt b-1)\) 3) \(\sqrt[3]{xy}(\sqrt[3]{x}+\sqrt[3]{y})\)
52489911
Factor each expression by extracting an appropriate radical factor. Assume all variables are nonnegative. 1) \(6+\sqrt{6}\) 2) \(3-\sqrt{3}\) 3) \(y-\sqrt{y}\) 4) \(x+\sqrt{xy}\)

Hints

- Rewrite a nonnegative number or variable as a product of two equal square roots. - Identify the radical factor shared by both terms. - Use the product property to rewrite \(\sqrt{xy}\) when useful. - Use \(\sqrt{u}\sqrt{u}=u\) for \(u\ge0\).

Solution

1. Since \(6=\sqrt{6}\cdot\sqrt{6}\), \(6+\sqrt{6}=\sqrt{6}(\sqrt{6}+1)\). 2. Since \(3=\sqrt{3}\cdot\sqrt{3}\), \(3-\sqrt{3}=\sqrt{3}(\sqrt{3}-1)\). 3. Since \(y=\sqrt{y}\cdot\sqrt{y}\), \(y-\sqrt{y}=\sqrt{y}(\sqrt{y}-1)\). 4. Rewrite \(x=\sqrt{x}\cdot\sqrt{x}\) and \(\sqrt{xy}=\sqrt{x}\sqrt{y}\). Then \(x+\sqrt{xy}=\sqrt{x}(\sqrt{x}+\sqrt{y})\).

Answer

1) \(\sqrt{6}(\sqrt{6}+1)\) 2) \(\sqrt{3}(\sqrt{3}-1)\) 3) \(\sqrt{y}(\sqrt{y}-1)\) 4) \(\sqrt{x}(\sqrt{x}+\sqrt{y})\)
52490511
Factor each expression completely. Assume every radicand is nonnegative. 1) \(x-\sqrt{x}\) 2) \(x+y-\sqrt{x+y}\)

Hints

- Rewrite the nonradical term as the square of a radical. - Identify the common radical factor in the two terms. - Check your factorization by multiplying.

Solution

1. Rewrite \(x=(\sqrt{x})^2\), then factor out \(\sqrt{x}\): \(x-\sqrt{x}=\sqrt{x}(\sqrt{x}-1)\). 2. Rewrite \(x+y=(\sqrt{x+y})^2\), then factor out \(\sqrt{x+y}\): \(x+y-\sqrt{x+y}=\sqrt{x+y}(\sqrt{x+y}-1)\).

Answer

1) \(\sqrt{x}(\sqrt{x}-1)\) 2) \(\sqrt{x+y}(\sqrt{x+y}-1)\)
52493511
Expand and simplify each expression using binomial formulas. 1) \((3\sqrt{2}+2)^2\) 2) \((2-\sqrt{7})^2\) 3) \((\sqrt{10}+\sqrt{5})^2\)

Hints

- Match each expression to the appropriate binomial-square formula. - Use \((\sqrt{u})^2=u\) for \(u\ge0\). - Square both the coefficient and the radical factor. - Simplify the radical in the middle term.

Solution

1. \((3\sqrt{2}+2)^2=18+12\sqrt{2}+4=22+12\sqrt{2}\). 2. \((2-\sqrt{7})^2=4-4\sqrt{7}+7=11-4\sqrt{7}\). 3. \((\sqrt{10}+\sqrt{5})^2=10+2\sqrt{50}+5=15+10\sqrt{2}\).

Answer

1) \(22+12\sqrt{2}\) 2) \(11-4\sqrt{7}\) 3) \(15+10\sqrt{2}\)
52497511
Simplify each expression as far as possible. Write the result as one radical or as a rational number. Assume all variables are positive. a) \(\sqrt[3]{\sqrt{64}}\) b) \(\sqrt[4]{\sqrt{x^2}}\) c) \(\sqrt[3]{\sqrt[5]{y^{10}}}\)

Hints

- Multiply radical indices for nested roots. - Reduce the resulting rational exponent. - Use the positivity assumptions when simplifying variable powers.

Solution

1. \(\sqrt[3]{\sqrt{64}}=\sqrt[6]{64}=2\). 2. \(\sqrt[4]{\sqrt{x^2}}=\sqrt[8]{x^2}=x^{\frac14}=\sqrt[4]{x}\). 3. \(\sqrt[3]{\sqrt[5]{y^{10}}}=\sqrt[15]{y^{10}}=y^{\frac23}=\sqrt[3]{y^2}\).

Answer

a) \(2\) b) \(\sqrt[4]{x}\) c) \(\sqrt[3]{y^2}\)
52504911
Evaluate \(x^2-4x+9\) for \(x=2+\sqrt{5}\).

Hints

- Substitute the given value directly. - Expand the squared binomial. - Look for terms that cancel.

Solution

1. Substitute to get \((2+\sqrt{5})^2-4(2+\sqrt{5})+9\). 2. Expand: \((2+\sqrt{5})^2=9+4\sqrt{5}\), and \(-4(2+\sqrt{5})=-8-4\sqrt{5}\). 3. Combining gives \(9+4\sqrt{5}-8-4\sqrt{5}+9=10\).

Answer

\(10\)
52533511
Find the domain of each expression over the real numbers. Write each answer using interval notation or inequalities. a) \(A(x)=\sqrt{5x-15}\) b) \(B(x)=\sqrt{12-4x}+\sqrt{x+2}\) c) \(C(x)=\frac{3}{\sqrt{2x-8}}\)

Hints

- A real square root requires a nonnegative radicand. - A square root in a denominator cannot equal zero. - When an expression contains two radicals, intersect their domain conditions. - Combine inequalities and excluded values carefully when writing each domain.

Solution

1. For a), require \(5x-15\ge0\), which gives \(x\ge3\). 2. For b), both radicands must be nonnegative. The conditions are \(12-4x\ge0\), so \(x\le3\), and \(x+2\ge0\), so \(x\ge-2\). Their intersection is \(-2\le x\le3\). 3. For c), the radicand in the denominator must be strictly positive: \(2x-8>0\), so \(x>4\).

Answer

a) \([3,\infty)\) b) \([-2,3]\) c) \((4,\infty)\)
52704111
Simplify each expression as far as possible. a) \(\sqrt[6]{27}\) b) \(5\sqrt[3]{\frac2{25}}\) c) \(\frac1{\sqrt[3]{4}}\)

Hints

- Rewrite radicands as powers when possible. - Move an outside coefficient into a radical by raising it to the radical index. - Complete the cube in the denominator before rationalizing.

Solution

1. \(\sqrt[6]{27}=\sqrt[6]{3^3}=3^{\frac12}=\sqrt3\). 2. \(5\sqrt[3]{\frac2{25}}=\sqrt[3]{125\cdot\frac2{25}}=\sqrt[3]{10}\). 3. Multiply by \(\frac{\sqrt[3]{2}}{\sqrt[3]{2}}\): \(\frac{\sqrt[3]{2}}{\sqrt[3]{8}}=\frac{\sqrt[3]{2}}2\).

Answer

a) \(\sqrt3\) b) \(\sqrt[3]{10}\) c) \(\frac{\sqrt[3]{2}}2\)
52808511
Compare each pair without approximating the radicals. Insert \(<\), \(>\), or \(=\), and justify your answer briefly. a) \(2\sqrt{14}\) ___ \(3\sqrt{6}\) b) \(0.5\sqrt{80}\) ___ \(2\sqrt{5}\) c) \(4\) ___ \(\sqrt{17}\)

Hints

- Move each positive coefficient under the radical by squaring it. - Compare positive square roots by comparing their radicands. - Rewrite a positive integer as the square root of its square when useful.

Solution

1. In a), \(2\sqrt{14}=\sqrt{56}\) and \(3\sqrt{6}=\sqrt{54}\). Since \(56>54\), \(2\sqrt{14}>3\sqrt{6}\). 2. In b), \(0.5\sqrt{80}=\sqrt{20}\) and \(2\sqrt{5}=\sqrt{20}\), so the values are equal. 3. In c), \(4=\sqrt{16}\), and \(16<17\). Therefore, \(4<\sqrt{17}\).

Answer

a) \(2\sqrt{14}>3\sqrt{6}\) b) \(0.5\sqrt{80}=2\sqrt{5}\) c) \(4<\sqrt{17}\)
52809111
Move the factor outside the radical under the radical sign: \((1-a)\sqrt{\frac{5}{a-1}}\), for \(a>1\).

Hints

- Determine the sign of the factor outside the radical first. - Rewrite the negative factor as a negative sign times a positive expression. - Square only the positive expression that moves under the radical. - Simplify common factors inside the radicand.

Solution

1. Since \(a>1\), \(1-a=-(a-1)\), where \(a-1>0\). 2. Keep the negative sign outside and square the positive factor when moving it under the radical: \(-(a-1)\sqrt{\frac{5}{a-1}}=-\sqrt{(a-1)^2\cdot\frac{5}{a-1}}\). 3. Simplifying the radicand gives \(-\sqrt{5(a-1)}\).

Answer

\(-\sqrt{5(a-1)}\)
52809711
Evaluate each expression and round the result to the nearest tenth. 1) \(\sqrt{40}\div\sqrt{5}\) 2) \(\sqrt{45}\div\sqrt{3}\) 3) \(\sqrt{21}\div\sqrt{7}\) 4) \(\sqrt{120}\div\sqrt{6}\)

Hints

- Combine the quotient of two square roots into one square root. - Simplify the quotient inside the radical before approximating. - Check the simplified radicand before using a decimal approximation. - Use the hundredths digit to round to the nearest tenth.

Solution

1. \(\sqrt{40}\div\sqrt{5}=\sqrt{8}\approx2.8\). 2. \(\sqrt{45}\div\sqrt{3}=\sqrt{15}\approx3.9\). 3. \(\sqrt{21}\div\sqrt{7}=\sqrt{3}\approx1.7\). 4. \(\sqrt{120}\div\sqrt{6}=\sqrt{20}\approx4.5\).

Answer

1) \(2.8\) 2) \(3.9\) 3) \(1.7\) 4) \(4.5\)
52879911
Let \(f(x)=\sqrt{4x+1}-2\). 1. Find the maximal real domain of \(f\). 2. Determine which points lie on the graph of \(f\): \(A(0, -1)\), \(B(2, 1)\), \(C(-1, -1)\), \(D(0.75, 0)\), and \(E(6, 3)\).

Hints

- Require the expression under the square root to be nonnegative. - For each point, substitute its x-coordinate and compare the result with its y-coordinate. - Check the domain before evaluating a point.

Solution

1. The radicand must be nonnegative: \(4x+1\ge0\), so \(x\ge-0.25\). The domain is \([-0.25, \infty)\). 2. For A, \(f(0)=\sqrt{1}-2=-1\), so A is on the graph. 3. For B, \(f(2)=\sqrt{9}-2=1\), so B is on the graph. 4. Point C is not on the graph because \(-1\) is outside the domain. 5. For D, \(f(0.75)=\sqrt{4}-2=0\), so D is on the graph. 6. For E, \(f(6)=\sqrt{25}-2=3\), so E is on the graph.

Answer

1. \([-0.25, \infty)\) 2. Points A, B, D, and E lie on the graph. Point C does not.
52880011
Let \(g(x)=\frac{4}{\sqrt{x}}\). 1. Explain without graphing why \(P(0, 0)\) cannot lie on the graph of \(g\). 2. Determine which points lie on the graph: \(A(1, 4)\), \(B(4, 2)\), \(C(0.25, 8)\), and \(D(16, 1)\).

Hints

- Combine the restrictions imposed by a square root and by a denominator. - Substitute each x-coordinate and compare the output with the stated y-coordinate. - Recall that \(\sqrt{0.25}=0.5\).

Solution

1. Because the square root is in the denominator, \(x\) must be positive. At \(x=0\), the denominator would be zero, so \(g(0)\) is undefined. Therefore, \(P\) cannot lie on the graph. 2. \(g(1)=\frac{4}{1}=4\), so A lies on the graph. 3. \(g(4)=\frac{4}{2}=2\), so B lies on the graph. 4. \(g(0.25)=\frac{4}{0.5}=8\), so C lies on the graph. 5. \(g(16)=\frac{4}{4}=1\), so D lies on the graph.

Answer

1. \(x=0\) is excluded because it makes the denominator zero. 2. All four points A, B, C, and D lie on the graph.
51008611
For \(a>0\) and \(b>0\), which expression is equivalent to \(\sqrt[3]{a^4b^5}\sqrt[6]{a^4b^3}\)? a) \(a^2b^2\) b) \(a^2b^2\sqrt b\) c) \(a^2b^2\sqrt[3]{b}\) d) \(a^2b^2\sqrt[6]{b}\)

Hints

- Rewrite each radical as a rational exponent. - Add exponents when multiplying powers with the same base. - Separate the whole-number part of the final exponent.

Solution

1. Rewrite the radicals as rational exponents: \(a^{\frac43}b^{\frac53}a^{\frac46}b^{\frac36}\). 2. Add exponents with the same base: \(a^{\frac43+\frac23}=a^2\) and \(b^{\frac{10}{6}+\frac36}=b^{\frac{13}{6}}\). 3. Since \(b^{\frac{13}{6}}=b^2b^{\frac16}\), the expression is \(a^2b^2\sqrt[6]{b}\).

Answer

d) \(a^2b^2\sqrt[6]{b}\)
51008711
For \(x\ge0\) and \(y\ge0\), which expression is equivalent to \(\sqrt{8x^2y+4x^3y^2}\)? a) \(2x\sqrt{2y+xy^2}\) b) \(4x\sqrt{2y+xy^2}\) c) \(2xy\sqrt{2+x}\) d) \(2x\sqrt{2y}+2xy\sqrt{x}\)

Hints

- Factor a perfect-square expression from the radicand. - Use the product property of square roots. - The conditions on \(x\) and \(y\) determine how \(\sqrt{x^2}\) simplifies.

Solution

1. Factor the greatest perfect-square factor from the radicand: \(8x^2y+4x^3y^2=4x^2(2y+xy^2)\). 2. Then \(\sqrt{4x^2(2y+xy^2)}=\sqrt{4x^2}\sqrt{2y+xy^2}\). 3. Because \(x\ge0\), \(\sqrt{4x^2}=2x\). Therefore, the equivalent expression is \(2x\sqrt{2y+xy^2}\).

Answer

a) \(2x\sqrt{2y+xy^2}\)
51016311
Simplify each expression as far as possible. Assume \(x>0\), \(y>0\), and \(z>0\). a) \(\frac{\sqrt{x^3y}}{\sqrt{xy^3}}\) b) \((\sqrt[3]{z^2}\sqrt{z})^6\) c) \((\sqrt{x}+\sqrt{y})(\sqrt{x}-\sqrt{y})(x+y)\) d) \(\frac{\sqrt[3]{x^2y}}{\sqrt[3]{x^{-1}y^4}}\)

Hints

- Treat each part separately because each uses a different structure. - Positivity lets you simplify roots without sign ambiguity. - Combine matching radicals in parts a and d, and look for a difference of squares in part c.

Solution

1. \(\frac{\sqrt{x^3y}}{\sqrt{xy^3}}=\sqrt{\frac{x^3y}{xy^3}}=\sqrt{\frac{x^2}{y^2}}=\frac{x}{y}\), using positivity. 2. \((\sqrt[3]{z^2}\sqrt{z})^6=(z^{\frac23}z^{\frac12})^6=(z^{\frac76})^6=z^7\). 3. \((\sqrt{x}+\sqrt{y})(\sqrt{x}-\sqrt{y})=x-y\). Then \((x-y)(x+y)=x^2-y^2\). 4. \(\frac{\sqrt[3]{x^2y}}{\sqrt[3]{x^{-1}y^4}}=\sqrt[3]{x^3y^{-3}}=\sqrt[3]{\frac{x^3}{y^3}}=\frac{x}{y}\).

Answer

a) \(\frac{x}{y}\) b) \(z^7\) c) \(x^2-y^2\) d) \(\frac{x}{y}\)
51428911
Square \(A\) has area \(32\,\text{cm}^2\), and square \(B\) has area \(50\,\text{cm}^2\). a) Find the side lengths \(a\) and \(b\) in the form \(k\sqrt{2}\), where \(k\) is a natural number. b) A rectangle has side lengths \(a\) and \(b\). Find its perimeter in the form \(m\sqrt{2}\,\text{cm}\).

Hints

- A square's side length is the square root of its area. - Factor a perfect square from each radicand. - Use the rectangle perimeter formula after finding its side lengths. - Like radical terms can be combined as like terms.

Solution

1. The side length of square \(A\) is \(a=\sqrt{32}=\sqrt{16\cdot2}=4\sqrt{2}\,\text{cm}\). 2. The side length of square \(B\) is \(b=\sqrt{50}=\sqrt{25\cdot2}=5\sqrt{2}\,\text{cm}\). 3. The rectangle's perimeter is \(P=2(a+b)=2(4\sqrt{2}+5\sqrt{2})=18\sqrt{2}\,\text{cm}\).

Answer

a) \(a=4\sqrt{2}\,\text{cm}\) and \(b=5\sqrt{2}\,\text{cm}\) b) \(18\sqrt{2}\,\text{cm}\)
51430411
Simplify each expression without a calculator. Write each result as an integer or a fraction in lowest terms. a) \(\sqrt{1\frac{7}{9}}\cdot\sqrt{2\frac{1}{4}}\) b) \(\sqrt{3\frac{1}{16}}\div\sqrt{1\frac{9}{16}}\) c) \(\sqrt{1\frac{11}{25}\cdot1\frac{9}{16}}\)

Hints

- Convert the mixed numbers to improper fractions. - Decide whether it is easier to simplify under one radical or take separate square roots. - When dividing fractions, multiply by the reciprocal.

Solution

1. For a), \(\sqrt{\frac{16}{9}}\cdot\sqrt{\frac{9}{4}}=\frac{4}{3}\cdot\frac{3}{2}=2\). 2. For b), \(\sqrt{\frac{49}{16}}\div\sqrt{\frac{25}{16}}=\frac{7}{4}\div\frac{5}{4}=\frac{7}{5}\). 3. For c), \(\sqrt{\frac{36}{25}\cdot\frac{25}{16}}=\sqrt{\frac{36}{16}}=\frac{3}{2}\).

Answer

a) \(2\) b) \(\frac{7}{5}\) c) \(\frac{3}{2}\)
51430911
Use the following calculations to investigate properties of square roots. a) Evaluate \(A=\sqrt{36\cdot4}\) and \(B=\sqrt{36}\cdot\sqrt{4}\). Compare the results. b) Evaluate \(C=\sqrt{64+36}\) and \(D=\sqrt{64}+\sqrt{36}\). Compare the results. c) What general conclusion can you draw from part b) about square roots and addition?

Hints

- Evaluate the quantity inside each radical before taking the square root. - Compare the final values, not just the forms of the expressions. - A property that works for multiplication may not work for addition.

Solution

1. \(A=\sqrt{144}=12\), and \(B=6\cdot2=12\). Therefore, \(A=B\), illustrating the product property \(\sqrt{ab}=\sqrt{a}\sqrt{b}\) for nonnegative \(a\) and \(b\). 2. \(C=\sqrt{100}=10\), while \(D=8+6=14\). Therefore, \(C\ne D\). 3. A square root does not distribute over addition. In general, \(\sqrt{a+b}\ne\sqrt{a}+\sqrt{b}\).

Answer

a) \(A=12\) and \(B=12\); the results are equal. b) \(C=10\) and \(D=14\); the results are not equal. c) In general, \(\sqrt{a+b}\ne\sqrt{a}+\sqrt{b}\).
51432811
Analyze each expression. a) Is \(\sqrt{x^2+x^2}=2x\) true for every \(x>0\)? Justify your answer. b) Simplify \(T=\sqrt{\sqrt{y^{16}}}\) as a power of \(y\).

Hints

- Combine like terms inside the radical first. - A square root does not distribute over addition. - Rewrite nested square roots using fractional exponents.

Solution

1. For a), \(\sqrt{x^2+x^2}=\sqrt{2x^2}=x\sqrt{2}\) because \(x>0\). Since \(\sqrt{2}\ne2\), the statement is false. 2. For b), \(\sqrt{\sqrt{y^{16}}}=(y^{16})^{1/4}=y^4\).

Answer

a) False; the left side equals \(x\sqrt{2}\), not \(2x\). b) \(y^4\)
51433611
Let \(T(x)=\sqrt{(x-4)^2}\). a) Find \(T(1)\) and \(T(7)\). b) A student claims, “The square and square root cancel, so \(\sqrt{(x-4)^2}=x-4\) for every real \(x\).” Determine exactly when the equation is true, and justify your answer using the definition of the principal square root.

Hints

- A principal square root is never negative. - Rewrite \(\sqrt{u^2}\) using absolute value. - When does \(|x-4|=x-4\)?

Solution

1. \(T(1)=\sqrt{(-3)^2}=3\), and \(T(7)=\sqrt{3^2}=3\). 2. For every real expression \(u\), \(\sqrt{u^2}=|u|\). Thus, \(\sqrt{(x-4)^2}=|x-4|\). 3. The equation \(|x-4|=x-4\) is true exactly when \(x-4\ge0\), or \(x\ge4\).

Answer

a) \(T(1)=3\) and \(T(7)=3\) b) The equation is true exactly when \(x\ge4\).
51433911
Simplify each expression completely. Pay close attention to the sign of the result. a) \(\sqrt{(-15)^2}\) b) \(\sqrt{(0.4)^2}\) c) \(\sqrt{(2-\sqrt{5})^2}\) d) \(\sqrt{y^2}\) for any \(y<0\)

Hints

- Use \(\sqrt{u^2}=|u|\). - Determine the sign of the expression inside each absolute value. - Compare \(2\) and \(\sqrt{5}\) by comparing their squares.

Solution

1. \(\sqrt{(-15)^2}=|-15|=15\). 2. \(\sqrt{(0.4)^2}=|0.4|=0.4\). 3. Since \(2<\sqrt{5}\), \(2-\sqrt{5}<0\). Therefore, \(\sqrt{(2-\sqrt{5})^2}=|2-\sqrt{5}|=\sqrt{5}-2\). 4. For \(y<0\), \(\sqrt{y^2}=|y|=-y\).

Answer

a) \(15\) b) \(0.4\) c) \(\sqrt{5}-2\) d) \(-y\)
51438511
Simplify each expression completely. Then name the smallest listed number set containing the result: \(\mathbb{N}\), \(\mathbb{Z}\), \(\mathbb{Q}\), or \(\mathbb{R}\). a) \(A=\sqrt{0.04}\) b) \(B=\sqrt{27}\div\sqrt{3}\) c) \(C=(1-\sqrt{2})^2\) d) \(D=\sqrt{10}\cdot\sqrt{0.4}\) e) \(E=\sqrt{(-7)^2}\)

Hints

- Use product and quotient properties of radicals. - Expand the square in part c). - Remember that \(\sqrt{x^2}=|x|\) for real \(x\).

Solution

1. \(A=\sqrt{0.04}=0.2=\frac{1}{5}\), so the smallest listed set is \(\mathbb{Q}\). 2. \(B=\sqrt{\frac{27}{3}}=\sqrt{9}=3\), so the smallest listed set is \(\mathbb{N}\). 3. \(C=(1-\sqrt{2})^2=1-2\sqrt{2}+2=3-2\sqrt{2}\), which is irrational. The smallest listed set is \(\mathbb{R}\). 4. \(D=\sqrt{10\cdot0.4}=\sqrt{4}=2\), so the smallest listed set is \(\mathbb{N}\). 5. \(E=\sqrt{(-7)^2}=|-7|=7\), so the smallest listed set is \(\mathbb{N}\).

Answer

a) \(0.2\in\mathbb{Q}\) b) \(3\in\mathbb{N}\) c) \(3-2\sqrt{2}\in\mathbb{R}\) d) \(2\in\mathbb{N}\) e) \(7\in\mathbb{N}\)
51441111
Simplify each expression completely. Unless otherwise stated, variables are real numbers. a) \(\sqrt{3a}\cdot\sqrt{12a}\), for \(a\ge0\) b) \(\sqrt{125x^2-44x^2}\) c) \(\sqrt{\frac{16a^2}{0.25}}\) d) \(\sqrt{(-15)^2}+\sqrt{b^2}\)

Hints

- Simplify products, differences, or quotients inside a radical before taking the square root. - Use \(\sqrt{u^2}=|u|\) unless the sign of \(u\) is known. - Dividing by a positive decimal less than \(1\) increases the value.

Solution

1. In a), \(\sqrt{3a}\sqrt{12a}=\sqrt{36a^2}=6a\), because \(a\ge0\). 2. In b), \(\sqrt{125x^2-44x^2}=\sqrt{81x^2}=9|x|\). 3. In c), \(\sqrt{\frac{16a^2}{0.25}}=\sqrt{64a^2}=8|a|\). 4. In d), \(\sqrt{(-15)^2}=15\) and \(\sqrt{b^2}=|b|\), so the result is \(15+|b|\).

Answer

a) \(6a\) b) \(9|x|\) c) \(8|a|\) d) \(15+|b|\)
51441211
Simplify each expression completely. a) \(\sqrt{2}(\sqrt{18}+\sqrt{50})\) b) \(\frac{\sqrt{0.04z^2}}{\sqrt{0.01z^2}}\), for \(z\ne0\) c) \(\sqrt{x^2y^2}-|xy|\) d) \(\frac{\sqrt{169c^2}}{\sqrt{1.69}}\)

Hints

- Distribute before combining products of square roots. - Simplify square roots of decimal perfect squares. - Use \(\sqrt{u^2}=|u|\). - Cancel a variable factor only when the stated condition makes it nonzero.

Solution

1. In a), distribute and combine products of radicals: \(\sqrt{36}+\sqrt{100}=6+10=16\). 2. In b), the numerator is \(0.2|z|\) and the denominator is \(0.1|z|\). Since \(z\ne0\), the quotient is \(2\). 3. In c), \(\sqrt{x^2y^2}=|xy|\), so the difference is \(0\). 4. In d), \(\sqrt{169c^2}=13|c|\) and \(\sqrt{1.69}=1.3\). Therefore, the quotient is \(10|c|\).

Answer

a) \(16\) b) \(2\) c) \(0\) d) \(10|c|\)
51442011
Answer each question about square roots. a) A student claims, “\(\sqrt{x^2}=x\) for every real \(x\).” Test the claim with \(x=5\) and \(x=-5\), then explain the correct rule. b) Simplify \(\frac{\sqrt{32z^5}}{\sqrt{2z}}\) for \(z>0\). c) Solve \(\sqrt{y}\cdot\sqrt{8}=4\).

Hints

- A principal square root cannot be negative. - Simplify the quotient inside one radical. - Square both sides after isolating or combining the radical expression.

Solution

1. For \(x=5\), \(\sqrt{5^2}=5\). For \(x=-5\), \(\sqrt{(-5)^2}=5\ne-5\). The correct rule is \(\sqrt{x^2}=|x|\). 2. For \(z>0\), \(\frac{\sqrt{32z^5}}{\sqrt{2z}}=\sqrt{16z^4}=4z^2\). 3. Combining the radicals gives \(\sqrt{8y}=4\). Squaring yields \(8y=16\), so \(y=2\).

Answer

a) The claim is false; \(\sqrt{x^2}=|x|\). b) \(4z^2\) c) \(y=2\)
51442311
For \(a>0\) and \(b>0\), simplify \(\sqrt{\frac{a^4b^6}{a^{-2}}}\) using exponent and radical properties. Then evaluate the expression for \(a=10^{-1}\) and \(b=10\).

Hints

- Simplify powers with the same base inside the radical first. - Taking a square root halves even exponents when the variables are positive. - Use the product property when separating the radical of a product. - Combine the powers of ten before evaluating.

Solution

1. Inside the radical, \(\frac{a^4}{a^{-2}}=a^6\), so the expression becomes \(\sqrt{a^6b^6}\). 2. Since \(a\) and \(b\) are positive, \(\sqrt{a^6b^6}=a^3b^3=(ab)^3\). 3. Substituting gives \((10^{-1}\cdot10)^3=(10^0)^3=1\).

Answer

Simplified expression: \(a^3b^3\) Value: \(1\)
51442611
Compare each pair without using a calculator. Rewrite both terms in the form \(\sqrt{n}\), then state which is greater or whether they are equal. a) \(6\sqrt{2}\) and \(5\sqrt{3}\) b) \(0.5\sqrt{80}\) and \(\frac{1}{3}\sqrt{180}\)

Hints

- Move each positive coefficient under the radical by squaring it. - Compare positive square roots by comparing their radicands. - Rewrite \(0.5\) as \(\frac{1}{2}\) if helpful.

Solution

1. In a), \(6\sqrt{2}=\sqrt{36\cdot2}=\sqrt{72}\), while \(5\sqrt{3}=\sqrt{25\cdot3}=\sqrt{75}\). Since \(75>72\), \(5\sqrt{3}>6\sqrt{2}\). 2. In b), \(0.5\sqrt{80}=\sqrt{0.25\cdot80}=\sqrt{20}\), and \(\frac{1}{3}\sqrt{180}=\sqrt{\frac{1}{9}\cdot180}=\sqrt{20}\). The two values are equal.

Answer

a) \(5\sqrt{3}>6\sqrt{2}\) b) \(0.5\sqrt{80}=\frac{1}{3}\sqrt{180}\)
51443811
For \(d,a,b\ge0\) and \(x,y\in\mathbb{R}\), simplify each expression completely using binomial formulas. a) \((\sqrt{11}-\sqrt{d})(\sqrt{11}+\sqrt{d})\) b) \((x\sqrt{5}+2y)(x\sqrt{5}-2y)\) c) \((\sqrt{8}+\sqrt{2})^2\) d) \((\sqrt{a}+\sqrt{b})^2-(a+b)\)

Hints

- Recognize conjugate products as differences of squares. - Expand the squared sum in part d) before subtracting. - Simplify products of radicals in cross terms.

Solution

1. \((\sqrt{11}-\sqrt{d})(\sqrt{11}+\sqrt{d})=11-d\). 2. \((x\sqrt{5}+2y)(x\sqrt{5}-2y)=5x^2-4y^2\). 3. \((\sqrt{8}+\sqrt{2})^2=8+2\sqrt{16}+2=18\). 4. \((\sqrt{a}+\sqrt{b})^2-(a+b)=a+2\sqrt{ab}+b-a-b=2\sqrt{ab}\).

Answer

a) \(11-d\) b) \(5x^2-4y^2\) c) \(18\) d) \(2\sqrt{ab}\)
51443911
For the stated variable conditions, find the value of the blank that makes each expression a perfect binomial square. Then write the squared-binomial form. a) \(x+2\sqrt{7x}+\square\), for \(x\ge0\) b) \(3a-\sqrt{24a}+\square\), for \(a\ge0\)

Hints

- Compare each expression with \((u\pm v)^2=u^2\pm2uv+v^2\). - Identify \(u\) and \(v\) from the first and middle terms. - The missing term is the square of the second binomial term.

Solution

1. In a), let \(u=\sqrt{x}\) and \(v=\sqrt{7}\). The middle term is \(2uv=2\sqrt{7x}\), so the missing term is \(v^2=7\). The expression is \((\sqrt{x}+\sqrt{7})^2\). 2. In b), let \(u=\sqrt{3a}\) and \(v=\sqrt{2}\). Then \(2uv=\sqrt{24a}\), so the missing term is \(v^2=2\). The expression is \((\sqrt{3a}-\sqrt{2})^2\).

Answer

a) \(\square=7\), giving \((\sqrt{x}+\sqrt{7})^2\) b) \(\square=2\), giving \((\sqrt{3a}-\sqrt{2})^2\)
51444411
Simplify each expression when possible. If an expression cannot be simplified, explain why briefly. a) \(\sqrt{9z^2-12z+4}\) b) \(\sqrt{r^2+s^2}\) c) \(\sqrt{4m^2+20mn+25n^2}\) d) \(\sqrt{c^2+c+\frac{1}{4}}\)

Hints

- Look for perfect-square trinomials under the radicals. - Do not distribute a square root over a sum. - Rewrite fractional constants as squares when checking a binomial pattern.

Solution

1. In a), \(9z^2-12z+4=(3z-2)^2\), so the result is \(|3z-2|\). 2. In b), \(r^2+s^2\) is not a perfect-square trinomial, and a square root does not distribute over addition. It cannot be simplified in general. 3. In c), \(4m^2+20mn+25n^2=(2m+5n)^2\), so the result is \(|2m+5n|\). 4. In d), \(c^2+c+\frac{1}{4}=\left(c+\frac{1}{2}\right)^2\), so the result is \(\left|c+\frac{1}{2}\right|\).

Answer

a) \(|3z-2|\) b) Cannot be simplified in general c) \(|2m+5n|\) d) \(\left|c+\frac{1}{2}\right|\)
51444511
Simplify each radical completely. Factor common terms from the radicand when helpful. a) \(\sqrt{2x^2+4x+2}\) b) \(\sqrt{0.01u^2-0.4uv+4v^2}\) c) \(\sqrt{p^2+4q^2-4pq}\) d) \(\sqrt{\frac{4}{9}a^2+\frac{4}{3}ab+b^2}\)

Hints

- Factor out a common numerical factor before looking for a perfect square. - Reorder terms when that makes a binomial-square pattern easier to see. - Treat decimal and fractional coefficients as possible squares.

Solution

1. In a), factor \(2\): \(\sqrt{2(x^2+2x+1)}=\sqrt{2(x+1)^2}=\sqrt{2}|x+1|\). 2. In b), \(0.01u^2-0.4uv+4v^2=(0.1u-2v)^2\), so the result is \(|0.1u-2v|\). 3. In c), reorder the terms: \(p^2-4pq+4q^2=(p-2q)^2\), so the result is \(|p-2q|\). 4. In d), the radicand is \(\left(\frac{2}{3}a+b\right)^2\), so the result is \(\left|\frac{2}{3}a+b\right|\).

Answer

a) \(\sqrt{2}|x+1|\) b) \(|0.1u-2v|\) c) \(|p-2q|\) d) \(\left|\frac{2}{3}a+b\right|\)
51444711
A student claims that \(\sqrt{(x-7)^2}=x-7\) for every real \(x\). a) Test the claim using \(x=3\). What do you observe? b) Fill in the radicand so the equation is true for all real \(a\) and \(b\): \(\sqrt{\square}=|4a-3b|\)

Hints

- Substitute the given value into both expressions. - A principal square root cannot be negative. - Square the expression inside the absolute value to build the radicand.

Solution

1. At \(x=3\), \(\sqrt{(3-7)^2}=\sqrt{16}=4\), but \(3-7=-4\). The claim is false. The correct identity is \(\sqrt{(x-7)^2}=|x-7|\). 2. To obtain \(|4a-3b|\), the radicand must be \((4a-3b)^2\). 3. Expanding gives \((4a-3b)^2=16a^2-24ab+9b^2\).

Answer

a) The claim is false because \(4\ne-4\). b) \(16a^2-24ab+9b^2\)
51444811
Let \(T(x)=\sqrt{\frac{1}{9}x^2-\frac{2}{3}x+1}\). a) Simplify \(T(x)\) completely. b) Find the domain of \(T\) over the real numbers. Explain. c) Compare \(\sqrt{(x-3)^2}\) and \(\sqrt{(3-x)^2}\). Are they equal for every real \(x\)? Explain.

Hints

- Match the radicand to a squared-binomial pattern. - A square of a real expression is never negative. - Opposite numbers have the same absolute value.

Solution

1. The radicand is a perfect square: \(\frac{1}{9}x^2-\frac{2}{3}x+1=\left(\frac{x}{3}-1\right)^2\). Thus, \(T(x)=\left|\frac{x}{3}-1\right|\). 2. A squared real expression is always nonnegative, so the radicand is defined for every real \(x\). The domain is \(\mathbb{R}\). 3. \(\sqrt{(x-3)^2}=|x-3|\) and \(\sqrt{(3-x)^2}=|3-x|\). Since \(3-x=-(x-3)\), the absolute values are equal for every real \(x\).

Answer

a) \(\left|\frac{x}{3}-1\right|\) b) \(\mathbb{R}\) c) Yes. Both expressions equal \(|x-3|\).
51446811
For \(a>0\), simplify completely: \(\frac{\sqrt{a^3}+2a\sqrt{a}}{\sqrt{a}}-a\)

Hints

- Rewrite \(\sqrt{a^3}\) by factoring out \(a^2\). - Combine like terms in the numerator. - The condition \(a>0\) allows cancellation of \(\sqrt{a}\).

Solution

1. Since \(a>0\), \(\sqrt{a^3}=a\sqrt{a}\). 2. The numerator becomes \(3a\sqrt{a}\), so the quotient is \(3a\). 3. Subtracting \(a\) gives \(2a\).

Answer

\(2a\)
51447111
Find the domain of \(T(a)=\sqrt{\frac{5}{a-3}}\) over the real numbers. Explain the restrictions on \(a\).

Hints

- Apply both the radical restriction and the denominator restriction. - Determine when a fraction with positive numerator is positive. - The denominator cannot equal zero.

Solution

1. The fraction under the radical must be nonnegative, and its denominator cannot be zero. 2. Because the numerator \(5\) is positive, the quotient is nonnegative only when \(a-3>0\). 3. Therefore, \(a>3\).

Answer

\(a>3\), or \((3,\infty)\)
51447211
For each expression, find all real values of \(k\) for which it is defined. Briefly justify your answer. a) \(\sqrt{k^2+10}\) b) \(\sqrt{-(k-2)^2}\) c) \(\sqrt{\frac{4}{k^2}}\)

Hints

- Squares are always nonnegative. - A real square root requires a nonnegative radicand. - Check separately whether any denominator can equal zero.

Solution

1. For a), \(k^2+10>0\) for every real \(k\), so the expression is defined for all real numbers. 2. For b), \(-(k-2)^2\le0\). It is nonnegative only when \((k-2)^2=0\), so \(k=2\). 3. For c), \(k\ne0\) is required by the denominator. For every nonzero \(k\), \(\frac{4}{k^2}>0\), so the expression is defined.

Answer

a) \(k\in\mathbb{R}\) b) \(k=2\) c) \(k\ne0\)
51496011
Simplify each expression. Work without a calculator and assume all variables are positive. a) \(\sqrt[4]{81a^{12}}\) b) \(\sqrt{\sqrt[3]{x^{18}}}\) c) \(\frac{\sqrt[5]{b^{13}}}{\sqrt[5]{b^3}}\) d) \((\sqrt[3]{y})^{-6}\)

Hints

- Rewrite constants as perfect powers matching the radical index. - Multiply exponents when raising a power to another power. - Combine radicals with the same index before simplifying.

Solution

1. Since \(81=3^4\), \(\sqrt[4]{81a^{12}}=\sqrt[4]{3^4a^{12}}=3a^3\). 2. \(\sqrt{\sqrt[3]{x^{18}}}=x^{18\cdot\frac13\cdot\frac12}=x^3\). 3. \(\frac{\sqrt[5]{b^{13}}}{\sqrt[5]{b^3}}=\sqrt[5]{b^{10}}=b^2\). 4. \((\sqrt[3]{y})^{-6}=(y^{\frac13})^{-6}=y^{-2}=\frac1{y^2}\).

Answer

a) \(3a^3\) b) \(x^3\) c) \(b^2\) d) \(y^{-2}=\frac1{y^2}\)
51496611
The product property for radicals states that \(\sqrt[n]{a}\sqrt[n]{b}=\sqrt[n]{ab}\) for \(a,b\geq0\) and integers \(n\geq2\). a) Justify this property by rewriting the radicals with rational exponents and applying an exponent property. b) Use the property to evaluate \(\sqrt[4]{2}\sqrt[4]{8}\). Show your work.

Hints

- Rewrite each radical as a power with exponent \(\frac1n\). - Apply the product property for powers with the same exponent. - In part b, combine the radicands first.

Solution

1. Rewrite the radicals: \(\sqrt[n]{a}\sqrt[n]{b}=a^{\frac1n}b^{\frac1n}\). 2. Apply the property \(u^rv^r=(uv)^r\): \(a^{\frac1n}b^{\frac1n}=(ab)^{\frac1n}=\sqrt[n]{ab}\). 3. \(\sqrt[4]{2}\sqrt[4]{8}=\sqrt[4]{16}=2\).

Answer

a) \(a^{\frac1n}b^{\frac1n}=(ab)^{\frac1n}=\sqrt[n]{ab}\) b) \(2\)
51496911
Write each expression as a single radical or without a radical. Assume \(x>0\), \(y>0\), and \(n\) is an integer greater than \(1\). a) \(\sqrt[n]{x^2}\sqrt[n]{x^3}\) b) \(\frac{\sqrt[3]{y^2}}{\sqrt[6]{y}}\) c) \(\sqrt{x}\sqrt[3]{x}\sqrt[6]{x}\)

Hints

- Combine matching radical indices directly. - For different indices, rewrite the radicals as rational exponents. - Add exponents when multiplying powers with the same base and subtract them when dividing.

Solution

1. \(\sqrt[n]{x^2}\sqrt[n]{x^3}=\sqrt[n]{x^5}\). 2. \(\frac{\sqrt[3]{y^2}}{\sqrt[6]{y}}=y^{\frac23-\frac16}=y^{\frac12}=\sqrt{y}\). 3. \(\sqrt{x}\sqrt[3]{x}\sqrt[6]{x}=x^{\frac12+\frac13+\frac16}=x^1=x\).

Answer

a) \(\sqrt[n]{x^5}\) b) \(\sqrt{y}\) c) \(x\)
51498811
Let \(T=\frac{\sqrt[3]{z^7}}{\sqrt[3]{z}}\) for \(z>0\). a) Simplify \(T\) to the form \(z^n\). b) Evaluate \(T\) for \(z=8\) without a calculator. c) A student claims, “If the radical index in \(\sqrt[n]{x^m}\) is doubled while the exponent in the radicand is halved, the value always stays the same.” Test the claim for \(x>0\) using \(\sqrt[4]{x^{12}}\).

Hints

- Combine the quotient under one cube root. - Use the simplified expression in part b. - In part c, compare the rational exponents before and after the proposed change.

Solution

1. \(T=\sqrt[3]{\frac{z^7}{z}}=\sqrt[3]{z^6}=z^2\). 2. For \(z=8\), \(T=8^2=64\). 3. The original expression is \(\sqrt[4]{x^{12}}=x^3\). Doubling the index and halving the exponent gives \(\sqrt[8]{x^6}=x^{\frac68}=x^{\frac34}\). These are not equal for all positive \(x\), so the claim is false.

Answer

a) \(z^2\) b) \(64\) c) The claim is false: \(\sqrt[4]{x^{12}}=x^3\), but \(\sqrt[8]{x^6}=x^{\frac34}\).
51541611
Find all natural numbers \(n>1\) for which \(\sqrt[n]{128}\sqrt[n]{8}\) is an integer.

Hints

- Combine the product under one radical. - Write \(1024\) as a power of \(2\). - Determine when the resulting exponent is a positive integer.

Solution

1. Combine the radicals: \(\sqrt[n]{128}\sqrt[n]{8}=\sqrt[n]{1024}\). 2. Since \(1024=2^{10}\), the expression is \(2^{\frac{10}{n}}\). 3. For this value to be an integer, \(\frac{10}{n}\) must be a positive integer. Thus \(n\) must be a divisor of \(10\). 4. The divisors of \(10\) greater than \(1\) are \(2\), \(5\), and \(10\).

Answer

\(n\in\{2,5,10\}\)
51541711
Let \(T_1=\sqrt[3]{\sqrt{a^{18}}}\) and \(T_2=\frac{\sqrt{a^5}\sqrt{a^7}}{\sqrt{a^6}}\), where \(a>0\). Simplify each expression step by step and determine whether they are equal for every \(a>0\).

Hints

- A root of a root multiplies the rational exponents. - Simplify the numerator and denominator of \(T_2\) under one square root. - Compare the two final powers of \(a\).

Solution

1. \(T_1=(a^{18})^{\frac12\cdot\frac13}=a^3\). 2. \(T_2=\sqrt{\frac{a^5a^7}{a^6}}=\sqrt{a^6}=a^3\), since \(a>0\). 3. Both expressions simplify to \(a^3\), so they are equal for every positive \(a\).

Answer

Yes. Both expressions simplify to \(a^3\).
51541911
Simplify the expression. Assume \(x>0\). \(\sqrt{x^3\sqrt[4]{x^2\sqrt{x^4}}}\)

Hints

- Simplify from the innermost radical outward. - Use the assumption \(x>0\) when taking even roots. - Combine powers with the same base before simplifying each radical.

Solution

1. Start with the innermost radical: \(\sqrt{x^4}=x^2\). 2. Then \(\sqrt[4]{x^2\cdot x^2}=\sqrt[4]{x^4}=x\). 3. Finally, \(\sqrt{x^3\cdot x}=\sqrt{x^4}=x^2\).

Answer

\(x^2\)
51555211
Simplify each expression completely, paying attention to domain conditions and absolute values. a) \(\sqrt{18x^2}\), for real \(x\) b) \(\frac{\sqrt{12y^3}}{\sqrt{3y}}\), for \(y>0\) c) \(\sqrt{(a-b)^2}-\sqrt{(b-a)^2}\), for real \(a\) and \(b\)

Hints

- Extract perfect-square factors from each radicand. - Use the quotient property for radicals when the quantities are defined. - Apply \(\sqrt{u^2}=|u|\). - Opposite expressions have equal absolute values.

Solution

1. In a), \(\sqrt{18x^2}=\sqrt{9\cdot2\cdot x^2}=3\sqrt{2}|x|\). 2. In b), combine the quotient under one radical: \(\sqrt{\frac{12y^3}{3y}}=\sqrt{4y^2}=2|y|=2y\), because \(y>0\). 3. In c), the expression becomes \(|a-b|-|b-a|\). Since \(b-a=-(a-b)\), the two absolute values are equal, so the result is \(0\).

Answer

a) \(3\sqrt{2}|x|\) b) \(2y\) c) \(0\)
51556011
Simplify completely: \((3\sqrt{2}-\sqrt{8})^2+\sqrt{3}(\sqrt{12}+\sqrt{27})\)

Hints

- Simplify each radical before combining terms. - Combine like radical terms inside each set of parentheses. - Follow the order of operations.

Solution

1. Since \(\sqrt{8}=2\sqrt{2}\), the first term is \((3\sqrt{2}-2\sqrt{2})^2=(\sqrt{2})^2=2\). 2. Since \(\sqrt{12}=2\sqrt{3}\) and \(\sqrt{27}=3\sqrt{3}\), the second term is \(\sqrt{3}(2\sqrt{3}+3\sqrt{3})=\sqrt{3}(5\sqrt{3})=15\). 3. Adding gives \(2+15=17\).

Answer

\(17\)
52355111
A security system presents a program with six independent challenges. The program answers each challenge correctly with probability \(p\). Access is granted only if all six challenges are answered correctly. Find the value of \(p\) that makes the overall probability of gaining access exactly \(50\%\).

Hints

- Write the overall probability as a product of six equal probabilities. - Form an equation involving \(p\). - Use a sixth root to reverse the sixth power.

Solution

1. Because all six independent challenges must be answered correctly, the overall probability is \(p^6\). 2. Set \(p^6=0.50\). 3. Take the sixth root: \(p=\sqrt[6]{0.50}\). 4. Numerically, \(p\approx 0.8909\).

Answer

\(p=\sqrt[6]{0.50}\approx 0.8909\), or about \(89.09\%\)
52452411
Let \(a=\sqrt{3}\) and \(b=\sqrt{12}\). Simplify each expression and determine whether the result is rational or irrational. 1) \(a+b\) 2) \(ab\) 3) \(b\div a\) 4) \(a^2+b^2\) 5) \((b-a)^2\)

Hints

- Rewrite \(\sqrt{12}\) in simplest radical form. - Use radical properties for multiplication and division. - Use a squared-binomial identity in the expression that contains one. - Simplify before classifying each result.

Solution

1. \(a+b=\sqrt{3}+\sqrt{12}=\sqrt{3}+2\sqrt{3}=3\sqrt{3}\), which is irrational. 2. \(ab=\sqrt{3}\sqrt{12}=\sqrt{36}=6\), which is rational. 3. \(b\div a=\sqrt{12}\div\sqrt{3}=\sqrt{4}=2\), which is rational. 4. \(a^2+b^2=3+12=15\), which is rational. 5. \((b-a)^2=(2\sqrt{3}-\sqrt{3})^2=(\sqrt{3})^2=3\), which is rational.

Answer

1) \(3\sqrt{3}\), irrational 2) \(6\), rational 3) \(2\), rational 4) \(15\), rational 5) \(3\), rational
52466911
Leon tries to prove that \(2=4\): 1. \((2-3)^2=(-1)^2=1\) 2. \((4-3)^2=1^2=1\) 3. Therefore, \((2-3)^2=(4-3)^2\). 4. He takes square roots: \(\sqrt{(2-3)^2}=\sqrt{(4-3)^2}\). 5. He writes \(2-3=4-3\). 6. He adds \(3\) to both sides and concludes \(2=4\). In which line does Leon make an error? Explain the error and correct line 5.

Hints

- Evaluate each side of line 5 separately. - Recall that a principal square root is nonnegative. - Apply \(\sqrt{u^2}=|u|\), especially when \(u\) may be negative. - Check how the rule behaves when the quantity being squared is negative.

Solution

1. Lines 1 through 4 are valid because both squared expressions equal \(1\). 2. The error occurs in line 5. In general, \(\sqrt{u^2}=|u|\), not \(u\). 3. The correct line is \(|2-3|=|4-3|\), which simplifies to \(1=1\). It does not imply \(2=4\).

Answer

The error is in line 5. It should be \(|2-3|=|4-3|\), because \(\sqrt{u^2}=|u|\).
52467011
Let \(T(x)=\sqrt{x^2-10x+25}\). a) Evaluate \(T(x)\) for \(x=8\) and \(x=2\). b) A student claims, “The expression simplifies to \(T(x)=x-5\).” Use your results from part a to check the claim. For which values of \(x\) is the student’s simplification correct?

Hints

- Rewrite the radicand using a squared-binomial pattern. - Substitute the given values into both the original expression and the proposed simplification. - A principal square root cannot be negative. - Determine when \(x-5\) is nonnegative.

Solution

1. The radicand is a perfect square: \(x^2-10x+25=(x-5)^2\). 2. For \(x=8\), \(T(8)=\sqrt{(8-5)^2}=\sqrt{3^2}=3\). 3. For \(x=2\), \(T(2)=\sqrt{(2-5)^2}=\sqrt{(-3)^2}=3\). 4. The proposed expression gives \(8-5=3\), so it works when \(x=8\). It gives \(2-5=-3\), so it does not work when \(x=2\). 5. In general, \(T(x)=\sqrt{(x-5)^2}=|x-5|\). This equals \(x-5\) exactly when \(x-5\ge0\), or \(x\ge5\).

Answer

a) \(T(8)=3\) and \(T(2)=3\) b) The claim is true for \(x=8\) but false for \(x=2\). The simplification \(T(x)=x-5\) is correct for \(x\ge5\).
52467711
Simplify \(T(x)=\sqrt{x^2+4x+4}-\sqrt{x^2-4x+4}\) for \(-2<x<2\).

Hints

- Rewrite each radicand as the square of a binomial. - Use the relationship between the square root of a square and absolute value. - Determine the signs of \(x+2\) and \(x-2\) on the given interval. - Use those signs to remove the absolute-value symbols.

Solution

1. Rewrite each radicand as a perfect square: \(T(x)=\sqrt{(x+2)^2}-\sqrt{(x-2)^2}\). 2. Apply \(\sqrt{u^2}=|u|\): \(T(x)=|x+2|-|x-2|\). 3. Because \(-2<x<2\), \(x+2>0\) and \(x-2<0\). Therefore, \(|x+2|=x+2\) and \(|x-2|=2-x\). 4. Thus, \(T(x)=(x+2)-(2-x)=2x\).

Answer

\(2x\)
52467811
Let \(E(y)=\frac{y+\sqrt{y^2-10y+25}}{2}\). Simplify the expression in each case. 1) \(y\ge5\) 2) \(y<5\)

Hints

- Rewrite the radicand as the square of a binomial. - Recall how absolute value changes when its input is negative. - Treat the two given ranges of \(y\) separately.

Solution

1. Rewrite the radicand as a perfect square: \(y^2-10y+25=(y-5)^2\). Therefore, \(E(y)=\frac{y+|y-5|}{2}\). 2. When \(y\ge5\), \(|y-5|=y-5\). Then \(E(y)=\frac{y+y-5}{2}=\frac{2y-5}{2}=y-2.5\). 3. When \(y<5\), \(|y-5|=5-y\). Then \(E(y)=\frac{y+5-y}{2}=\frac{5}{2}=2.5\).

Answer

1) For \(y\ge5\): \(y-2.5\) 2) For \(y<5\): \(2.5\)
52468611
Use the identity \(\sqrt{x^2}=|x|\) to simplify each expression completely. The final answers should not contain radicals. a) \(\sqrt{x^2\cdot y^4}\), for \(x<0\) and real \(y\) b) \(\sqrt{\frac{25a^2}{b^2}}\), for \(a>0\) and \(b<0\) c) For which real numbers \(z\) is \(\sqrt{z^2}=-z\)?

Hints

- Replace the square root of each squared expression with an absolute value. - Use the stated sign conditions to remove the absolute-value symbols. - In part c, determine when a number’s absolute value equals its opposite.

Solution

1. In a), \(\sqrt{x^2\cdot y^4}=\sqrt{x^2}\sqrt{(y^2)^2}=|x||y^2|\). Since \(y^2\ge0\), \(|y^2|=y^2\). Since \(x<0\), \(|x|=-x\). The result is \(-xy^2\). 2. In b), \(\sqrt{\frac{25a^2}{b^2}}=\frac{5|a|}{|b|}\). Because \(a>0\), \(|a|=a\), and because \(b<0\), \(|b|=-b\). Therefore, the result is \(\frac{5a}{-b}=-\frac{5a}{b}\). 3. In c), \(\sqrt{z^2}=|z|\), so the equation is \(|z|=-z\). This is true exactly when \(z\le0\).

Answer

a) \(-xy^2\) b) \(-\frac{5a}{b}\) c) \(z\le0\)
52468711
Simplify each expression completely. Pay close attention to the sign of the expression inside each pair of parentheses. a) \(\sqrt{(5-\sqrt{26})^2}\) b) \(\sqrt{12(\sqrt{3}-2)^2}\)

Hints

- Recall what happens when you take the principal square root of a squared expression. - A principal square root is never negative. - Compare \(5\) with \(\sqrt{26}\) without using a calculator. - Extract the perfect-square factor from \(\sqrt{12}\).

Solution

1. In a), \(\sqrt{(5-\sqrt{26})^2}=|5-\sqrt{26}|\). 2. Since \(5=\sqrt{25}<\sqrt{26}\), the expression \(5-\sqrt{26}\) is negative. Therefore, \(|5-\sqrt{26}|=\sqrt{26}-5\). 3. In b), \(\sqrt{12(\sqrt{3}-2)^2}=\sqrt{12}|\sqrt{3}-2|\). 4. Since \(\sqrt{12}=2\sqrt{3}\) and \(\sqrt{3}<2\), \(|\sqrt{3}-2|=2-\sqrt{3}\). 5. Thus, \(2\sqrt{3}(2-\sqrt{3})=4\sqrt{3}-6\).

Answer

a) \(\sqrt{26}-5\) b) \(4\sqrt{3}-6\)
52469011
For \(a\ge0\) and \(b<3\), simplify completely: \(\sqrt{a^7(b-3)^2}\)

Hints

- Separate the largest even power of \(a\) from the factor left under the radical. - A square root of a squared expression produces an absolute value. - Use the condition \(b<3\) to simplify that absolute value.

Solution

1. Rewrite the radicand as \(a^6\cdot a\cdot(b-3)^2\). 2. Since \(a\ge0\), \(\sqrt{a^6}=a^3\). 3. Because \(b<3\), \(b-3<0\), so \(\sqrt{(b-3)^2}=|b-3|=3-b\). 4. Therefore, the simplified expression is \(a^3(3-b)\sqrt{a}\).

Answer

\(a^3(3-b)\sqrt{a}\)
52469611
Consider \(A=\sqrt[3]{\frac{x^6y^4}{27z^3}}\). a) Simplify the expression by extracting perfect-cube factors. b) Does the simplification remain valid when \(y\) or \(z\) is negative? Explain using the properties of odd-index roots.

Hints

- Identify factors whose exponents are multiples of \(3\). - Recall that cube roots of negative numbers are real. - For an odd index, \(\sqrt[n]{u^n}=u\) without an absolute value.

Solution

1. Rewrite the radicand as \(\frac{(x^2)^3y^3y}{3^3z^3}\). 2. Extract the perfect cubes: \(A=\frac{x^2y\sqrt[3]{y}}{3z}\). 3. A cube root is defined for every real radicand, and \(\sqrt[3]{u^3}=u\) for every real \(u\). Therefore the simplification remains valid for negative \(y\) or \(z\), provided \(z\neq0\).

Answer

a) \(\frac{x^2y\sqrt[3]{y}}{3z}\) b) Yes. It is valid for all real \(x\) and \(y\) and all real \(z\neq0\).
52469911
Extract all possible factors from each radical. Assume the variables make the expressions real. 1) \(\sqrt[3]{54a^4}\) 2) \(\sqrt[3]{16(x+2)^5}\) 3) \(\sqrt[4]{80y^7}\)

Hints

- Factor each radicand into a perfect power and a remaining factor. - Match the perfect-power exponent to the radical index. - For an even-index radical, use the domain to determine whether an absolute value is needed.

Solution

1. \(\sqrt[3]{54a^4}=\sqrt[3]{27a^3\cdot2a}=3a\sqrt[3]{2a}\). 2. \(\sqrt[3]{16(x+2)^5}=\sqrt[3]{8(x+2)^3\cdot2(x+2)^2}=2(x+2)\sqrt[3]{2(x+2)^2}\). 3. For the fourth root to be real, \(y\geq0\). Then \(\sqrt[4]{80y^7}=\sqrt[4]{16y^4\cdot5y^3}=2y\sqrt[4]{5y^3}\).

Answer

1) \(3a\sqrt[3]{2a}\) 2) \(2(x+2)\sqrt[3]{2(x+2)^2}\) 3) \(2y\sqrt[4]{5y^3}\)
52470011
Simplify each expression by extracting perfect-power factors. For part 1, assume \(c\neq0\). For part 2, assume \(a\leq-1\) or \(a>0\). 1) \(\sqrt[3]{\frac{8b^4}{27c^6}}\) 2) \(\sqrt[4]{\frac1{a^8}+\frac1{a^9}}\) 3) \(\sqrt[3]{a^6b-a^6c}\)

Hints

- Combine fractions before simplifying a radical. - Factor out common powers whose exponents are multiples of the radical index. - Use the stated domain conditions when extracting even powers.

Solution

1. \(\sqrt[3]{\frac{8b^4}{27c^6}}=\sqrt[3]{\frac{2^3b^3b}{3^3(c^2)^3}}=\frac{2b}{3c^2}\sqrt[3]{b}\). 2. Combine the fractions: \(\frac1{a^8}+\frac1{a^9}=\frac{a+1}{a^9}=\frac1{a^8}\cdot\frac{a+1}{a}\). Since \(a^2>0\), the fourth root is \(\frac1{a^2}\sqrt[4]{\frac{a+1}{a}}\). 3. \(\sqrt[3]{a^6(b-c)}=a^2\sqrt[3]{b-c}\).

Answer

1) \(\frac{2b}{3c^2}\sqrt[3]{b}\) 2) \(\frac1{a^2}\sqrt[4]{\frac{a+1}{a}}\) 3) \(a^2\sqrt[3]{b-c}\)
52471011
Simplify each expression by extracting perfect-power factors, and state its real domain. 1) \(\sqrt[4]{48(b-2)^5}\) 2) \(\sqrt[3]{-24(c+1)^7}\) 3) \(\sqrt{x^5+x^4}\)

Hints

- Factor each radicand before extracting powers. - Odd-index radicals allow negative radicands. - For part 3, factor out the greatest common power of \(x\) and analyze the sign of the remaining factor.

Solution

1. The fourth root requires \(b\geq2\). Then \(\sqrt[4]{48(b-2)^5}=\sqrt[4]{16(b-2)^4\cdot3(b-2)}=2(b-2)\sqrt[4]{3(b-2)}\). 2. The cube root is defined for every real \(c\). Factoring gives \(\sqrt[3]{-8(c+1)^6\cdot3(c+1)}=-2(c+1)^2\sqrt[3]{3(c+1)}\). 3. Factor the radicand: \(x^5+x^4=x^4(x+1)\). It is nonnegative exactly when \(x\geq-1\). Thus \(\sqrt{x^4(x+1)}=x^2\sqrt{x+1}\).

Answer

1) \(2(b-2)\sqrt[4]{3(b-2)}\), for \(b\geq2\) 2) \(-2(c+1)^2\sqrt[3]{3(c+1)}\), for \(c\in\mathbb R\) 3) \(x^2\sqrt{x+1}\), for \(x\geq-1\)
52471711
1. Compare each pair by moving the positive coefficient under the radical. Insert \(<\), \(>\), or \(=\). a) \(4\sqrt{3}\) ___ \(3\sqrt{5}\) b) \(2\sqrt{10}\) ___ \(3\sqrt{4.5}\) 2. A student claims that \(x\sqrt{2}=\sqrt{2x^2}\) for every real number \(x\). Test the claim using \(x=-3\), and explain why it is not true for all real \(x\).

Hints

- A positive coefficient moved under a square root must be squared. - Compare positive radicals by comparing their radicands. - Remember that a principal square root is never negative. - Use \(\sqrt{x^2}=|x|\).

Solution

1. In a), \(4\sqrt{3}=\sqrt{48}\) and \(3\sqrt{5}=\sqrt{45}\), so \(4\sqrt{3}>3\sqrt{5}\). 2. In b), \(2\sqrt{10}=\sqrt{40}\) and \(3\sqrt{4.5}=\sqrt{40.5}\), so \(2\sqrt{10}<3\sqrt{4.5}\). 3. For \(x=-3\), the left side is \(-3\sqrt{2}\), while the right side is \(\sqrt{2(-3)^2}=\sqrt{18}=3\sqrt{2}\). They are not equal. 4. In general, \(\sqrt{2x^2}=|x|\sqrt{2}\), not \(x\sqrt{2}\). The two expressions agree only when \(x\ge0\).

Answer

1. a) \(4\sqrt{3}>3\sqrt{5}\) b) \(2\sqrt{10}<3\sqrt{4.5}\) 2. The claim is false. At \(x=-3\), \(-3\sqrt{2}\ne3\sqrt{2}\). In general, \(\sqrt{2x^2}=|x|\sqrt{2}\).
52471811
Rewrite each expression so that no factor remains outside the radical. Simplify the radicand completely. Assume all variables are positive. a) \(\frac{a}{2}\sqrt{\frac{8}{a}}\) b) \(3b^2\sqrt{\frac{1}{3b^3}}\) c) \(\frac{2}{3x}\sqrt{18x^3}\)

Hints

- A positive factor moved under a square root must be squared. - Simplify numerical factors and variable powers after combining them under the radical. - Use \((mn)^2=m^2n^2\) when moving a product under a radical. - Use the assumption that every variable is positive.

Solution

1. In a), move \(\frac{a}{2}\) under the radical by squaring it: \(\sqrt{\left(\frac{a}{2}\right)^2\cdot\frac{8}{a}}=\sqrt{2a}\). 2. In b), move \(3b^2\) under the radical: \(\sqrt{(3b^2)^2\cdot\frac{1}{3b^3}}=\sqrt{3b}\). 3. In c), move \(\frac{2}{3x}\) under the radical: \(\sqrt{\left(\frac{2}{3x}\right)^2\cdot18x^3}=\sqrt{8x}\).

Answer

a) \(\sqrt{2a}\) b) \(\sqrt{3b}\) c) \(\sqrt{8x}\)
52472211
Analyze each transformation. In parts a and b, all variables are positive real numbers. In part c, assume \(b\geq0\). a) Write \(x\sqrt[4]{x^3}\) in the form \(\sqrt[4]{\dots}\). b) A student claims \(2y^2\sqrt[3]{3y}=\sqrt[3]{6y^7}\). Check the claim and correct it if necessary. c) Explain why the rule \(a\sqrt b=\sqrt{a^2b}\) does not generally hold when \(a<0\).

Hints

- Raise an outside factor to the radical index before moving it inside. - Apply the power to both the coefficient and the variable factor. - A principal square root is always nonnegative.

Solution

1. \(x\sqrt[4]{x^3}=\sqrt[4]{x^4x^3}=\sqrt[4]{x^7}\). 2. The outside factor must be cubed: \(2y^2\sqrt[3]{3y}=\sqrt[3]{(2y^2)^3\cdot3y}=\sqrt[3]{24y^7}\). The claim is false. 3. If \(a<0\) and \(b>0\), then \(a\sqrt b<0\), but \(\sqrt{a^2b}\geq0\). Moving a negative factor inside an even-index radical loses its sign.

Answer

a) \(\sqrt[4]{x^7}\) b) The claim is false; the correct expression is \(\sqrt[3]{24y^7}\). c) For \(a<0\) and \(b>0\), the left side is negative while the right side is nonnegative.
52473211
Simplify each expression by extracting perfect-power factors or applying exponent properties. Assume \(x\), \(y\), \(a\), \(b\), and \(z\) are positive real numbers and \(n,k\geq2\) are natural numbers. 1) \(\sqrt[4]{x^9y^4}\) 2) \(\sqrt[n]{a^{n+2}b^{3n}}\) 3) \(\frac{\sqrt[k]{z^{2k+1}}}{z}\)

Hints

- Split each exponent into a multiple of the radical index plus a remainder. - Extract factors whose exponents are divisible by the radical index. - Simplify matching powers in a numerator and denominator.

Solution

1. \(\sqrt[4]{x^9y^4}=\sqrt[4]{x^8y^4\cdot x}=x^2y\sqrt[4]{x}\). 2. \(\sqrt[n]{a^{n+2}b^{3n}}=\sqrt[n]{a^na^2(b^3)^n}=ab^3\sqrt[n]{a^2}\). 3. \(\frac{\sqrt[k]{z^{2k+1}}}{z}=\frac{z^2\sqrt[k]{z}}{z}=z\sqrt[k]{z}\).

Answer

1) \(x^2y\sqrt[4]{x}\) 2) \(ab^3\sqrt[n]{a^2}\) 3) \(z\sqrt[k]{z}\)
52474111
Move each outside factor into the radicand, then simplify. a) \(2x^2\sqrt{\frac1{4x^3}+\frac3{2x^4}}\), where \(x\ge-6\) and \(x\ne0\) b) \(\frac{a-b}{a}\sqrt[3]{\frac{a^4}{a^2-2ab+b^2}}\), where \(a\ne0\) and \(a\ne b\)

Hints

- Raise the outside factor to the radical index before moving it inside; for the square root, first note that \(2x^2>0\) on the stated domain. - In part b, recognize a perfect-square trinomial. - Simplify products and quotients inside the radical after combining them.

Solution

1. \(2x^2\sqrt{\frac1{4x^3}+\frac3{2x^4}}=\sqrt{4x^4\left(\frac1{4x^3}+\frac3{2x^4}\right)}=\sqrt{x+6}\). 2. Since \(a^2-2ab+b^2=(a-b)^2\), \(\frac{a-b}{a}\sqrt[3]{\frac{a^4}{(a-b)^2}}=\sqrt[3]{\left(\frac{a-b}{a}\right)^3\frac{a^4}{(a-b)^2}}=\sqrt[3]{a(a-b)}\).

Answer

a) \(\sqrt{x+6}\) b) \(\sqrt[3]{a(a-b)}\)
52474211
Move the outside factor into the radical and simplify. a) \(\frac1{k+1}\sqrt{k^3+3k^2+3k+1}\), for \(k>-1\) b) \(\frac{x}{y}\sqrt[3]{\frac{y^4}{x^2}+\frac{y^3}{x^2}}\), for \(x>0\) and \(y>0\)

Hints

- Recognize the binomial cube in part a. - Factor \(y^3\) in part b. - Raise each outside factor to the radical index before moving it inside.

Solution

1. Since \(k>-1\), \(k+1>0\). Also, \(k^3+3k^2+3k+1=(k+1)^3\). Therefore \(\frac1{k+1}\sqrt{(k+1)^3}=\sqrt{\frac{(k+1)^3}{(k+1)^2}}=\sqrt{k+1}\). 2. Factor inside the cube root: \(\frac{y^4}{x^2}+\frac{y^3}{x^2}=\frac{y^3(y+1)}{x^2}\). Then \(\frac{x}{y}\sqrt[3]{\frac{y^3(y+1)}{x^2}}=\sqrt[3]{\frac{x^3}{y^3}\cdot\frac{y^3(y+1)}{x^2}}=\sqrt[3]{x(y+1)}\).

Answer

a) \(\sqrt{k+1}\) b) \(\sqrt[3]{x(y+1)}\)
52474411
Let \(T=\sqrt[n]{\frac{x}{a^k}}\), where \(a>0\), \(x>0\), and \(n\) and \(k\) are natural numbers with \(n>k\). a) Rewrite \(T\) so that no fraction remains inside the radical. b) Apply your result to \(\sqrt[5]{\frac2{a^2}}\). c) Separately consider the case in which \(k\) is a multiple of \(n\). A student claims that the denominator root can then be evaluated directly without multiplying the fraction by another factor. Test the claim with an example.

Hints

- Multiply by a power of \(a\) that makes the denominator \(a^n\). - Use the exponent difference \(n-k\). - If the denominator exponent is already a multiple of the radical index, extract it directly.

Solution

1. Multiply the radicand by \(\frac{a^{n-k}}{a^{n-k}}\): \(T=\sqrt[n]{\frac{xa^{n-k}}{a^n}}=\frac{\sqrt[n]{xa^{n-k}}}{a}\). 2. For \(n=5\) and \(k=2\), \(\sqrt[5]{\frac2{a^2}}=\frac{\sqrt[5]{2a^3}}a\). 3. If \(k=mn\), then \(\sqrt[n]{\frac{x}{a^{mn}}}=\frac{\sqrt[n]{x}}{a^m}\). For example, \(\sqrt[3]{\frac5{2^6}}=\frac{\sqrt[3]{5}}4\). The claim is true because the denominator is already a perfect \(n\)th power.

Answer

a) \(\frac{\sqrt[n]{xa^{n-k}}}{a}\) b) \(\frac{\sqrt[5]{2a^3}}a\) c) The claim is true; for example, \(\sqrt[3]{\frac5{2^6}}=\frac{\sqrt[3]{5}}4\).
52475611
Move the outside factor into the radical and simplify the radicand. Assume all expressions are defined, \(x+y>0\), and \(m>5\). a) \((x+y)\sqrt{\frac1{x^2-y^2}}\) b) \(\frac{a^2}{b}\sqrt[3]{\frac{b^4}{a^5}}\) c) \((m-5)\sqrt[4]{\frac1{m^2-10m+25}}\)

Hints

- Factor denominators using identities such as the difference of squares. - Raise an outside fraction to the radical index before moving it inside. - Look for a perfect-square trinomial in part c.

Solution

1. Since \(x^2-y^2=(x+y)(x-y)\), \((x+y)\sqrt{\frac1{x^2-y^2}}=\sqrt{\frac{(x+y)^2}{(x+y)(x-y)}}=\sqrt{\frac{x+y}{x-y}}\). 2. \(\frac{a^2}{b}\sqrt[3]{\frac{b^4}{a^5}}=\sqrt[3]{\frac{a^6}{b^3}\cdot\frac{b^4}{a^5}}=\sqrt[3]{ab}\). 3. Since \(m^2-10m+25=(m-5)^2\), \((m-5)\sqrt[4]{\frac1{(m-5)^2}}=\sqrt[4]{\frac{(m-5)^4}{(m-5)^2}}=\sqrt[4]{(m-5)^2}=\sqrt{m-5}\).

Answer

a) \(\sqrt{\frac{x+y}{x-y}}\) b) \(\sqrt[3]{ab}\) c) \(\sqrt{m-5}\)
52475811
Move the outside factor into the radical and simplify. Assume all variables are positive. a) \(x\sqrt{\frac3x}\) b) \(a\sqrt[3]{\frac{b}{a^2}}\) c) \(y^2\sqrt[4]{\frac1{y^7}}\)

Hints

- Raise the outside factor to the radical index. - Multiply powers and then subtract exponents when canceling. - Use the positivity assumptions to move factors inside an even-index radical.

Solution

1. \(x\sqrt{\frac3x}=\sqrt{x^2\cdot\frac3x}=\sqrt{3x}\). 2. \(a\sqrt[3]{\frac{b}{a^2}}=\sqrt[3]{a^3\cdot\frac{b}{a^2}}=\sqrt[3]{ab}\). 3. \(y^2\sqrt[4]{\frac1{y^7}}=\sqrt[4]{y^8\cdot\frac1{y^7}}=\sqrt[4]{y}\).

Answer

a) \(\sqrt{3x}\) b) \(\sqrt[3]{ab}\) c) \(\sqrt[4]{y}\)
52476411
Write each expression as a constant multiple of one radical, with no fraction inside the radical. Assume all variables are positive. a) \(m\sqrt[3]{\frac{n}{2m^2}}\) b) \(y\sqrt[4]{\frac{x}{8y^3}}\)

Hints

- First move the outside variable inside the radical. - Then make the denominator a perfect power matching the radical index. - Extract the radical of that denominator.

Solution

1. Move \(m\) inside the cube root: \(m\sqrt[3]{\frac{n}{2m^2}}=\sqrt[3]{\frac{mn}{2}}\). Multiply the fraction by \(\frac4{4}\): \(\sqrt[3]{\frac{4mn}{8}}=\frac12\sqrt[3]{4mn}\). 2. Move \(y\) inside the fourth root: \(y\sqrt[4]{\frac{x}{8y^3}}=\sqrt[4]{\frac{xy}{8}}\). Multiply the fraction by \(\frac2{2}\): \(\sqrt[4]{\frac{2xy}{16}}=\frac12\sqrt[4]{2xy}\).

Answer

a) \(\frac12\sqrt[3]{4mn}\) b) \(\frac12\sqrt[4]{2xy}\)
52476511
Simplify each expression. Assume all variables are positive. a) \(b^2\sqrt{\frac{18}{b^3}}\) b) \(\frac{x}{3}\sqrt[3]{\frac{54}{x^2}}\)

Hints

- Move the outside factor inside by raising it to the radical index. - Simplify the resulting powers and numerical factors. - Extract any remaining perfect square or perfect cube.

Solution

1. \(b^2\sqrt{\frac{18}{b^3}}=\sqrt{b^4\cdot\frac{18}{b^3}}=\sqrt{18b}=3\sqrt{2b}\). 2. \(\frac{x}{3}\sqrt[3]{\frac{54}{x^2}}=\sqrt[3]{\frac{x^3}{27}\cdot\frac{54}{x^2}}=\sqrt[3]{2x}\).

Answer

a) \(3\sqrt{2b}\) b) \(\sqrt[3]{2x}\)
52476811
Let \(T(x)=\sqrt{18x^3-24x^2+8x}\). a) Factor \(2x\) from the radicand, and then factor the remaining trinomial as a perfect square. b) Simplify \(T(x)\) completely. State the domain of \(T\) over the real numbers.

Hints

- Factor out the greatest common numerical factor and the smallest power of \(x\). - Look for the pattern \(a^2-2ab+b^2\) in the remaining trinomial. - Use \(\sqrt{u^2}=|u|\) when extracting a squared factor. - Determine when the entire radicand is nonnegative.

Solution

1. Factor \(2x\) from the radicand: \(18x^3-24x^2+8x=2x(9x^2-12x+4)\). 2. The trinomial is a perfect square: \(9x^2-12x+4=(3x-2)^2\). 3. Therefore, \(T(x)=\sqrt{2x(3x-2)^2}=|3x-2|\sqrt{2x}\). 4. For the original radical to be real, \(2x(3x-2)^2\ge0\). The squared factor is nonnegative, and its zero occurs at \(x=\frac{2}{3}\), which is already nonnegative. For every \(x<0\), the product is negative. Thus, the domain is \(x\ge0\).

Answer

a) \(2x(3x-2)^2\) b) \(T(x)=|3x-2|\sqrt{2x}\); domain: \([0,\infty)\)
52477111
Move the outside factor into the cube root and simplify the radicand. Assume \(x>0\), \(a>0\), and \(b>0\). 1) \(2x\sqrt[3]{1+\frac1{8x^3}}\) 2) \(\frac{a}{b}\sqrt[3]{\frac{b^3}{a^2}-\frac{b^4}{a^3}}\)

Hints

- Cube the outside factor before moving it inside. - Distribute that factor across every term in the radicand. - Simplify powers in each resulting fraction.

Solution

1. \(2x\sqrt[3]{1+\frac1{8x^3}}=\sqrt[3]{8x^3\left(1+\frac1{8x^3}\right)}=\sqrt[3]{8x^3+1}\). 2. \(\frac{a}{b}\sqrt[3]{\frac{b^3}{a^2}-\frac{b^4}{a^3}}=\sqrt[3]{\frac{a^3}{b^3}\left(\frac{b^3}{a^2}-\frac{b^4}{a^3}\right)}=\sqrt[3]{a-b}\).

Answer

1) \(\sqrt[3]{8x^3+1}\) 2) \(\sqrt[3]{a-b}\)
52477211
A student claims that \(A=\frac{x}{3}\sqrt[3]{\frac{54}{x^3}+\frac{27}{x^2}}\) is equivalent to \(B=\sqrt[3]{x+2}\) for every \(x>0\). Verify the claim algebraically.

Hints

- Move the outside fraction into the cube root. - Cube both its numerator and denominator. - Distribute and simplify the two terms in the radicand.

Solution

1. Move \(\frac{x}{3}\) inside the cube root by cubing it: \(A=\sqrt[3]{\frac{x^3}{27}\left(\frac{54}{x^3}+\frac{27}{x^2}\right)}\). 2. Simplify the radicand: \(\frac{x^3}{27}\cdot\frac{54}{x^3}+\frac{x^3}{27}\cdot\frac{27}{x^2}=2+x\). 3. Thus \(A=\sqrt[3]{x+2}=B\), so the claim is true.

Answer

The claim is true: \(A=\sqrt[3]{x+2}=B\).
52477311
Simplify the expression for \(x>0\), \(y>0\), and a natural number \(k\geq2\): \(\frac{2}{xy^2}\sqrt[k]{x^{k+3}y^{2k}}\)

Hints

- Separate exponents that are multiples of \(k\). - Extract the corresponding perfect \(k\)th powers. - Cancel the extracted factors with the denominator outside the radical.

Solution

1. Split the radicand as \(x^kx^3(y^2)^k\). 2. Extract the perfect \(k\)th powers: \(\sqrt[k]{x^{k+3}y^{2k}}=xy^2\sqrt[k]{x^3}\). 3. Multiply by the outside factor and cancel: \(\frac{2}{xy^2}\cdot xy^2\sqrt[k]{x^3}=2\sqrt[k]{x^3}\).

Answer

\(2\sqrt[k]{x^3}\)
52477711
Move the outside factor into the radical and simplify. Assume all variables are positive and \(n\geq2\) is a natural number. \(a^2\sqrt[n]{\frac{b}{a^{2n-1}}}\)

Hints

- Rewrite the outside factor as an \(n\)th root. - Combine the two radicals. - Subtract exponents when dividing powers with the same base.

Solution

1. Rewrite \(a^2\) as an \(n\)th root: \(a^2=\sqrt[n]{a^{2n}}\). 2. Combine the radicals and simplify the power of \(a\): \(\sqrt[n]{a^{2n}\cdot\frac{b}{a^{2n-1}}}=\sqrt[n]{ab}\).

Answer

\(\sqrt[n]{ab}\)
52477811
Rewrite the expression so that no fraction remains inside the radical. Assume it is defined, \(x+y>0\), and \(n>2\) is a natural number. \(\sqrt[n]{\frac{xy^2}{(x+y)^{n-2}}}\)

Hints

- Make the denominator exponent equal to \(n\). - Multiply both numerator and denominator by the same factor. - Then extract the perfect \(n\)th power from the denominator.

Solution

1. Multiply the radicand fraction by \(\frac{(x+y)^2}{(x+y)^2}\) so the denominator becomes an exact \(n\)th power: \(\sqrt[n]{\frac{xy^2(x+y)^2}{(x+y)^n}}\). 2. Since \(x+y>0\), extract the denominator: \(\frac1{x+y}\sqrt[n]{xy^2(x+y)^2}\).

Answer

\(\frac1{x+y}\sqrt[n]{xy^2(x+y)^2}\)
52477911
Let \(T(x)=\sqrt{(x-4)^2}-x\). a) Simplify \(T(x)\) without radicals when \(x\ge4\). b) Simplify \(T(x)\) without radicals when \(x<4\). c) Use the relationship between square roots and absolute value to explain why the two cases give different expressions.

Hints

- Consider what happens when a negative number is squared and then its principal square root is taken. - A principal square root is always nonnegative. - Rewrite the radical using the definition of absolute value. - Test one value on each side of \(4\) to see how the expression behaves.

Solution

1. Apply \(\sqrt{u^2}=|u|\): \(T(x)=|x-4|-x\). 2. When \(x\ge4\), \(x-4\ge0\), so \(|x-4|=x-4\). Then \(T(x)=(x-4)-x=-4\). 3. When \(x<4\), \(x-4<0\), so \(|x-4|=4-x\). Then \(T(x)=(4-x)-x=4-2x\). 4. The expression inside the absolute value changes sign at \(x=4\), so the rule for removing the absolute-value symbols changes there.

Answer

a) \(T(x)=-4\) b) \(T(x)=4-2x\) c) Since \(\sqrt{(x-4)^2}=|x-4|\), the expression changes form when \(x-4\) changes sign at \(x=4\).
52478011
Consider \(Q(k)=(k-2)\sqrt{\frac{5}{(k-2)^2}}\). Simplify the expression step by step to show that, for \(k\ne2\), it can take only two constant values. Find the value when \(k>2\), the value when \(k<2\), and state what happens when \(k=2\).

Hints

- Use the quotient property to separate the numerator and denominator under the radical. - Apply \(\sqrt{u^2}=|u|\). - Consider the numerator and denominator of the resulting fraction separately. - Be careful when canceling a factor against an absolute value.

Solution

1. For \(k\ne2\), \(\sqrt{\frac{5}{(k-2)^2}}=\frac{\sqrt{5}}{\sqrt{(k-2)^2}}=\frac{\sqrt{5}}{|k-2|}\). 2. Thus, \(Q(k)=\frac{(k-2)\sqrt{5}}{|k-2|}\). 3. When \(k>2\), \(|k-2|=k-2\), so \(Q(k)=\sqrt{5}\). 4. When \(k<2\), \(|k-2|=-(k-2)\), so \(Q(k)=-\sqrt{5}\). 5. When \(k=2\), the denominator \((k-2)^2\) is zero, so the original expression is undefined.

Answer

For \(k>2\), \(Q(k)=\sqrt{5}\). For \(k<2\), \(Q(k)=-\sqrt{5}\). For \(k=2\), \(Q(k)\) is undefined.
52478611
Analyze transformations involving higher-index radicals. a) Simplify \(3y^2\sqrt[3]{\frac2{9y^4}}\) for \(y\neq0\) by moving the outside factor into the cube root. b) A student claims, “To move \(x\) inside a fourth root, multiply it by \(4\).” Check the claim by correctly rewriting \(x\sqrt[4]{2}\) for \(x>0\), and explain the error.

Hints

- Match the power applied to an outside factor with the radical index. - Apply the power to every factor in the outside product. - Test whether the proposed transformation preserves the original value.

Solution

1. \(3y^2\sqrt[3]{\frac2{9y^4}}=\sqrt[3]{(3y^2)^3\cdot\frac2{9y^4}}=\sqrt[3]{6y^2}\). 2. For \(x>0\), \(x\sqrt[4]{2}=\sqrt[4]{x^4}\sqrt[4]{2}=\sqrt[4]{2x^4}\). 3. The student confused multiplication with exponentiation. To move a factor inside an \(n\)th root, raise it to the \(n\)th power.

Answer

a) \(\sqrt[3]{6y^2}\) b) \(\sqrt[4]{2x^4}\); the factor must be raised to the fourth power, not multiplied by \(4\).
52479211
Determine whether each sum or difference can be combined into one like-radical term. If it can, simplify it. a) \(2\sqrt[4]{48}-\sqrt[4]{243}\) b) \(\sqrt[3]{\frac29}+\sqrt[3]{0.75}\)

Hints

- Simplify each radical before deciding whether the terms are like radicals. - Make denominators inside radicals into perfect powers when needed. - Add or subtract only the coefficients of like radical terms.

Solution

1. \(\sqrt[4]{48}=\sqrt[4]{16\cdot3}=2\sqrt[4]{3}\), so \(2\sqrt[4]{48}=4\sqrt[4]{3}\). Also, \(\sqrt[4]{243}=\sqrt[4]{81\cdot3}=3\sqrt[4]{3}\). The difference is \(\sqrt[4]{3}\). 2. \(\sqrt[3]{\frac29}=\frac13\sqrt[3]{6}\), and \(\sqrt[3]{0.75}=\sqrt[3]{\frac34}=\frac12\sqrt[3]{6}\). Therefore the sum is \(\left(\frac13+\frac12\right)\sqrt[3]{6}=\frac56\sqrt[3]{6}\).

Answer

a) \(\sqrt[4]{3}\) b) \(\frac56\sqrt[3]{6}\)
52479811
Simplify the expression by first combining the fractions inside the cube root. Assume \(u>0\) and \(v>0\). \(\frac{3u}{v^2}\sqrt[3]{\frac{v^7}{9u^2}-\frac{v^6}{27u^3}}\)

Hints

- Combine the two fractions inside the radical. - Factor the numerator of the resulting fraction. - Extract perfect cubes that cancel with the outside coefficient.

Solution

1. Use the common denominator \(27u^3\): \(\frac{v^7}{9u^2}-\frac{v^6}{27u^3}=\frac{3uv^7-v^6}{27u^3}=\frac{v^6(3uv-1)}{27u^3}\). 2. Extract perfect cubes: \(\sqrt[3]{\frac{v^6(3uv-1)}{27u^3}}=\frac{v^2}{3u}\sqrt[3]{3uv-1}\). 3. The outside factors cancel, leaving \(\sqrt[3]{3uv-1}\).

Answer

\(\sqrt[3]{3uv-1}\)
52480611
Determine which radical terms are like terms after simplification. Assume \(k>1\). \(T_1=\sqrt[3]{k^4-k^3}\) \(T_2=\sqrt[3]{125k-125}\) \(T_3=\sqrt[3]{k^2-1}\)

Hints

- Factor each radicand. - Extract any perfect cubes. - Compare the remaining cube-root parts.

Solution

1. \(T_1=\sqrt[3]{k^3(k-1)}=k\sqrt[3]{k-1}\). 2. \(T_2=\sqrt[3]{125(k-1)}=5\sqrt[3]{k-1}\). 3. \(T_3=\sqrt[3]{(k-1)(k+1)}\), which has a different simplified radicand. 4. Therefore only \(T_1\) and \(T_2\) are like radical terms.

Answer

Only \(T_1\) and \(T_2\) are like radical terms.
52481111
Determine whether each pair consists of like radical terms after simplification. Assume all variables are positive and \(n\geq4\) is a natural number. a) \(\sqrt[3]{x^4y^5}\) and \(\sqrt[3]{xy^8}\) b) \(\sqrt[n]{a^{2n+3}b}\) and \(\sqrt[n]{\frac{a^2}{b^{n-1}}}\)

Hints

- Extract powers whose exponents are multiples of the radical index. - Make a denominator inside a radical into a perfect \(n\)th power. - Compare the remaining radical parts.

Solution

1. \(\sqrt[3]{x^4y^5}=xy\sqrt[3]{xy^2}\), and \(\sqrt[3]{xy^8}=y^2\sqrt[3]{xy^2}\). The pair has the same radical part, so the terms are like terms. 2. \(\sqrt[n]{a^{2n+3}b}=a^2\sqrt[n]{a^3b}\). Also, \(\sqrt[n]{\frac{a^2}{b^{n-1}}}=\frac1b\sqrt[n]{a^2b}\). The radical parts differ, so the terms are not like terms.

Answer

a) The terms are like radical terms. b) The terms are not like radical terms.
52481211
A student claims that \(A=\sqrt[k]{x^{2k+1}y}\) and \(B=\sqrt[k]{\frac{x}{y^{k-1}}}\) are like radical terms for all \(x>0\), \(y>0\), and natural numbers \(k>1\). Check the claim by simplifying both terms. If the claim is true, identify the common radical part.

Hints

- Extract the factor \(x^{2k}\) from the first radical. - Make the denominator of the second radicand a perfect \(k\)th power. - Compare the remaining radical parts.

Solution

1. \(A=\sqrt[k]{x^{2k}xy}=x^2\sqrt[k]{xy}\). 2. Multiply the radicand of \(B\) by \(\frac{y}{y}\): \(B=\sqrt[k]{\frac{xy}{y^k}}=\frac1y\sqrt[k]{xy}\). 3. Both expressions have the radical part \(\sqrt[k]{xy}\), so the claim is true.

Answer

The claim is true. The common radical part is \(\sqrt[k]{xy}\).
52481411
Without using a calculator, determine the greater value in each pair. Justify your answer algebraically. a) \(2\sqrt{5}\) or \(\sqrt{19}\) b) \(\sqrt{2}+\sqrt{3}\) or \(\sqrt{10}\)

Hints

- Move a positive coefficient under the radical by squaring it. - For two positive expressions, compare their squares. - Expand a squared sum of radicals with a binomial identity. - Compare the remaining radicals using nearby perfect squares.

Solution

1. In a), \(2\sqrt{5}=\sqrt{20}\). Since \(20>19\), \(2\sqrt{5}>\sqrt{19}\). 2. In b), both values are positive, so compare their squares. \((\sqrt{2}+\sqrt{3})^2=5+2\sqrt{6}=5+\sqrt{24}\), while \((\sqrt{10})^2=10=5+\sqrt{25}\). 3. Since \(\sqrt{24}<\sqrt{25}\), \((\sqrt{2}+\sqrt{3})^2<10\). Therefore, \(\sqrt{2}+\sqrt{3}<\sqrt{10}\).

Answer

a) \(2\sqrt{5}>\sqrt{19}\) b) \(\sqrt{10}>\sqrt{2}+\sqrt{3}\)
52481511
Simplify each expression by extracting perfect-square factors and combining like radicals. Then approximate the result to the nearest hundredth. a) \(4\sqrt{18}-2\sqrt{50}+\sqrt{8}\) b) \(\frac{1}{3}\sqrt{27}+\sqrt{12}-0.5\sqrt{48}\)

Hints

- Factor each radicand as a perfect square times another factor. - Combine only radicals with the same radicand. - Use the thousandths digit to round to the nearest hundredth.

Solution

1. For a), \(4\sqrt{18}-2\sqrt{50}+\sqrt{8}=12\sqrt{2}-10\sqrt{2}+2\sqrt{2}=4\sqrt{2}\approx5.66\). 2. For b), \(\frac{1}{3}\sqrt{27}+\sqrt{12}-0.5\sqrt{48}=\sqrt{3}+2\sqrt{3}-2\sqrt{3}=\sqrt{3}\approx1.73\).

Answer

a) \(4\sqrt{2}\approx5.66\) b) \(\sqrt{3}\approx1.73\)
52481611
Let \(T=\sqrt{150}-\sqrt{54}+\sqrt{24}\). a) Simplify \(T\) completely. b) Determine whether the result is rational or irrational. Briefly justify your answer. c) Show step by step that \(2\sqrt{0.5}+\sqrt{18}\) has the same value as \(4\sqrt{2}\).

Hints

- Extract the greatest perfect-square factor from each radicand. - Determine whether \(\sqrt{6}\) is rational. - Rewrite \(0.5\) as \(\frac{1}{2}\) and simplify its square root. - Rationalize any radical denominator that remains.

Solution

1. \(T=\sqrt{25\cdot6}-\sqrt{9\cdot6}+\sqrt{4\cdot6}=5\sqrt{6}-3\sqrt{6}+2\sqrt{6}=4\sqrt{6}\). 2. The result is irrational because \(\sqrt{6}\) is irrational and multiplying it by the nonzero rational number \(4\) preserves irrationality. 3. For part c), \(2\sqrt{0.5}=2\sqrt{\frac{1}{2}}=\sqrt{2}\), and \(\sqrt{18}=3\sqrt{2}\). Therefore, \(2\sqrt{0.5}+\sqrt{18}=\sqrt{2}+3\sqrt{2}=4\sqrt{2}\).

Answer

a) \(T=4\sqrt{6}\) b) Irrational c) \(2\sqrt{0.5}+\sqrt{18}=\sqrt{2}+3\sqrt{2}=4\sqrt{2}\)
52481911
Simplify each expression. Assume all variables are positive. a) \(2y\sqrt[4]{\frac3{8y^3}}\) b) \(\sqrt{18a^5+27a^4}\) c) \(\sqrt[6]{64x^2}\)

Hints

- Move an outside factor inside by raising it to the radical index. - Factor common perfect powers from a sum. - Rewrite numerical factors as powers matching the radical index.

Solution

1. \(2y\sqrt[4]{\frac3{8y^3}}=\sqrt[4]{16y^4\cdot\frac3{8y^3}}=\sqrt[4]{6y}\). 2. \(\sqrt{18a^5+27a^4}=\sqrt{9a^4(2a+3)}=3a^2\sqrt{2a+3}\). 3. \(\sqrt[6]{64x^2}=\sqrt[6]{2^6x^2}=2x^{\frac13}=2\sqrt[3]{x}\).

Answer

a) \(\sqrt[4]{6y}\) b) \(3a^2\sqrt{2a+3}\) c) \(2\sqrt[3]{x}\)
52482111
Simplify each expression completely by extracting perfect-square factors and combining like radicals. 1) \(3\sqrt{75}-2\sqrt{27}+\sqrt{108}\) 2) \(\sqrt{50}+2\sqrt{8}-\sqrt{162}\) 3) \(\sqrt{20}-\sqrt{0.45}+\sqrt{\frac{1}{5}}\)

Hints

- Factor a perfect square from each radicand. - Combine radical terms only after they have the same radicand. - Rewrite decimals and fractions in forms that are easier to simplify under a square root. - Rationalize a denominator when a radical remains below the fraction bar.

Solution

1. \(3\sqrt{75}-2\sqrt{27}+\sqrt{108}=15\sqrt{3}-6\sqrt{3}+6\sqrt{3}=15\sqrt{3}\). 2. \(\sqrt{50}+2\sqrt{8}-\sqrt{162}=5\sqrt{2}+4\sqrt{2}-9\sqrt{2}=0\). 3. \(\sqrt{20}-\sqrt{0.45}+\sqrt{\frac{1}{5}}=2\sqrt{5}-\frac{3\sqrt{5}}{10}+\frac{\sqrt{5}}{5}=\frac{19\sqrt{5}}{10}\).

Answer

1) \(15\sqrt{3}\) 2) \(0\) 3) \(\frac{19\sqrt{5}}{10}\)
52482211
Analyze each radical relationship. a) Determine whether \(\sqrt{12}+\sqrt{48}=\sqrt{108}\) is true or false. b) Simplify \((3\sqrt{20}-\sqrt{45})-(\sqrt{80}-\sqrt{5})\). Determine whether the result is rational or irrational.

Hints

- Simplify each radical separately before comparing or combining. - Distribute the subtraction across the second set of parentheses. - Do not add radicands unless a valid radical property applies. - A radical expression can simplify to a rational number.

Solution

1. \(\sqrt{12}+\sqrt{48}=2\sqrt{3}+4\sqrt{3}=6\sqrt{3}\), and \(\sqrt{108}=6\sqrt{3}\). Therefore, the equation is true. 2. \((3\sqrt{20}-\sqrt{45})-(\sqrt{80}-\sqrt{5})=(6\sqrt{5}-3\sqrt{5})-(4\sqrt{5}-\sqrt{5})=3\sqrt{5}-3\sqrt{5}=0\). 3. The result \(0\) is rational.

Answer

a) True; both sides equal \(6\sqrt{3}\). b) The value is \(0\), which is rational.
52482411
Determine whether the two terms in each pair are like radical terms after simplification. Assume the radicands are positive and no denominator is zero. a) \(A=\sqrt{\frac{x^2-y^2}{x-y}}\) and \(B=\sqrt{x+y}\) b) \(A=\sqrt[3]{a^4-a^3b}\) and \(B=\sqrt[3]{\frac{a-b}{a^3}}\)

Hints

- Factor a difference of squares in part a. - Factor the radicand of the first term in part b. - Extract a perfect cube from the numerator or denominator.

Solution

1. In part a, \(x^2-y^2=(x-y)(x+y)\), so \(A=\sqrt{x+y}=B\). The terms are identical. 2. In part b, \(A=\sqrt[3]{a^3(a-b)}=a\sqrt[3]{a-b}\). Also, \(B=\frac1a\sqrt[3]{a-b}\). They have the same cube-root part, so they are like radical terms.

Answer

a) The terms are identical and therefore like radical terms. b) The terms are like radical terms with radical part \(\sqrt[3]{a-b}\).
52482511
Simplify each expression by extracting perfect-power factors. Assume all variables are positive and \(n\geq4\) and \(k\geq2\) are natural numbers. 1) \(\sqrt[n]{x^{3n}y^{n+2}}\) 2) \(\sqrt[k]{a^{2k+1}b^{k-1}}\) 3) \(\sqrt[n]{\frac{p^{n+3}}{q^{2n}}}\)

Hints

- Split exponents into multiples of the radical index plus a remainder. - Extract the factors with divisible exponents. - Treat numerator and denominator separately when useful.

Solution

1. \(\sqrt[n]{x^{3n}y^{n+2}}=x^3y\sqrt[n]{y^2}\). 2. \(\sqrt[k]{a^{2k+1}b^{k-1}}=a^2\sqrt[k]{ab^{k-1}}\). 3. \(\sqrt[n]{\frac{p^{n+3}}{q^{2n}}}=\frac{p}{q^2}\sqrt[n]{p^3}\).

Answer

1) \(x^3y\sqrt[n]{y^2}\) 2) \(a^2\sqrt[k]{ab^{k-1}}\) 3) \(\frac{p}{q^2}\sqrt[n]{p^3}\)
52482611
Determine whether each transformation is correct. Show a step-by-step check. Assume all variables are positive, \(n\geq2\), and \(k\geq1\). 1) \(\sqrt[n]{a^{2n+1}b^{n+2}}=a^2b\sqrt[n]{ab^2}\) 2) \(\sqrt[k+1]{\frac{x^{k+2}}{y^{k+1}}}=\frac{x}{y}\sqrt[k+1]{x}\)

Hints

- Separate powers whose exponents match the radical index. - Simplify the left side of each equation independently. - Use the quotient property for radicals in part 2.

Solution

1. \(\sqrt[n]{a^{2n+1}b^{n+2}}=\sqrt[n]{a^{2n}ab^nb^2}=a^2b\sqrt[n]{ab^2}\). The transformation is correct. 2. \(\sqrt[k+1]{\frac{x^{k+2}}{y^{k+1}}}=\frac{\sqrt[k+1]{x^{k+1}x}}{\sqrt[k+1]{y^{k+1}}}=\frac{x}{y}\sqrt[k+1]{x}\). The transformation is correct.

Answer

1) Correct 2) Correct
52483211
Simplify the expression. Assume \(x\geq0\) and \(y\geq0\). \((\sqrt[3]{27x}+\sqrt{64y})-(2\sqrt[3]{8x}-\sqrt{4y})\)

Hints

- Extract perfect cubes and perfect squares. - Distribute the negative sign across the second parentheses. - Combine only terms with the same radical part.

Solution

1. \(\sqrt[3]{27x}=3\sqrt[3]{x}\), \(\sqrt[3]{8x}=2\sqrt[3]{x}\), \(\sqrt{64y}=8\sqrt y\), and \(\sqrt{4y}=2\sqrt y\). 2. Substitute and distribute the subtraction: \(3\sqrt[3]{x}+8\sqrt y-4\sqrt[3]{x}+2\sqrt y\). 3. Combine like radical terms to get \(-\sqrt[3]{x}+10\sqrt y\).

Answer

\(-\sqrt[3]{x}+10\sqrt y\)
52483611
Show step by step that the value of the expression is a natural number. \(\sqrt[3]{9}(\sqrt[3]{3}+\sqrt[3]{24})-\frac{\sqrt[3]{375}}{\sqrt[3]{3}}\)

Hints

- Distribute the factor outside the parentheses. - Combine cube roots in products and quotients. - Look for perfect cubes after combining radicands.

Solution

1. Distribute the first cube root: \(\sqrt[3]{9}\sqrt[3]{3}+\sqrt[3]{9}\sqrt[3]{24}=\sqrt[3]{27}+\sqrt[3]{216}=3+6\). 2. Simplify the quotient: \(\frac{\sqrt[3]{375}}{\sqrt[3]{3}}=\sqrt[3]{125}=5\). 3. Therefore the expression equals \(3+6-5=4\), which is a natural number.

Answer

\(4\)
52483811
Simplify completely: \((\sqrt{45}-1.5\sqrt{12})-(2\sqrt{20}-\sqrt{48})+\sqrt{27}\)

Hints

- Simplify every radical first. - A minus sign before parentheses changes the signs inside. - Combine terms only when their radicands match.

Solution

1. Rewrite the radicals: \(\sqrt{45}=3\sqrt{5}\), \(1.5\sqrt{12}=3\sqrt{3}\), \(2\sqrt{20}=4\sqrt{5}\), \(\sqrt{48}=4\sqrt{3}\), and \(\sqrt{27}=3\sqrt{3}\). 2. Remove parentheses carefully: \(3\sqrt{5}-3\sqrt{3}-4\sqrt{5}+4\sqrt{3}+3\sqrt{3}\). 3. Combine like radicals to obtain \(4\sqrt{3}-\sqrt{5}\).

Answer

\(4\sqrt{3}-\sqrt{5}\)
52484111
Simplify \(A=\sqrt{4x^2-12x+9}+\sqrt{4x^2+12x+9}\) for \(-1.5\le x\le1.5\).

Hints

- Rewrite each radicand using a squared-binomial pattern. - Use absolute value when taking the square root of a squared expression. - Determine the sign of each expression inside the absolute-value symbols on the given interval. - Recall how \(|u|\) simplifies when \(u\) is negative.

Solution

1. Rewrite each radicand as a perfect square: \(4x^2-12x+9=(2x-3)^2\) and \(4x^2+12x+9=(2x+3)^2\). 2. Therefore, \(A=|2x-3|+|2x+3|\). 3. On the interval \(-1.5\le x\le1.5\), \(2x-3\le0\), so \(|2x-3|=3-2x\). Also, \(2x+3\ge0\), so \(|2x+3|=2x+3\). 4. Thus, \(A=(3-2x)+(2x+3)=6\).

Answer

\(6\)
52484211
Simplify \(T=\sqrt{a^2c-2abc+b^2c}-\sqrt{a^2c+2abc+b^2c}\), given that \(c>0\) and \(a>b>0\).

Hints

- Factor the common factor from each radicand. - Look for squared-binomial patterns. - Use the conditions on \(a\) and \(b\) to remove the absolute-value symbols correctly. - Pay close attention to signs when subtracting the second expression.

Solution

1. Factor \(c\) from each radicand: \(T=\sqrt{c(a^2-2ab+b^2)}-\sqrt{c(a^2+2ab+b^2)}\). 2. Use the squared-binomial patterns: \(T=\sqrt{c(a-b)^2}-\sqrt{c(a+b)^2}\). 3. Extract the squared factors: \(T=\sqrt{c}|a-b|-\sqrt{c}|a+b|\). 4. Since \(a>b>0\), both \(a-b\) and \(a+b\) are positive. Therefore, \(T=\sqrt{c}(a-b)-\sqrt{c}(a+b)\). 5. Combine like terms: \(T=\sqrt{c}(a-b-a-b)=-2b\sqrt{c}\).

Answer

\(-2b\sqrt{c}\)
52484911
Let \(A=(\sqrt{7}+\sqrt{2})^2\) and \(B=(\sqrt{7}+\sqrt{2})(\sqrt{7}-\sqrt{2})\). a) Expand and simplify both expressions. b) Use the structure of the expressions to explain why \(B\) is rational while \(A\) is irrational.

Hints

- Identify the binomial-square and difference-of-squares patterns. - Square each radical carefully. - Which expansion keeps a cross term, and which cancels it?

Solution

1. Using the square of a binomial, \(A=7+2\sqrt{14}+2=9+2\sqrt{14}\). 2. Using the difference of squares, \(B=7-2=5\). 3. In \(A\), the middle term \(2\sqrt{14}\) remains and is irrational. In \(B\), the two cross terms cancel, leaving only the difference of the squared radicals, which is rational.

Answer

a) \(A=9+2\sqrt{14}\) and \(B=5\) b) The cross term remains in \(A\), but the conjugate factors in \(B\) cancel the cross terms and leave \(7-2\).
52485111
Simplify completely: \(\sqrt{45}-\sqrt{20}+\sqrt{125}-\sqrt{80}+\sqrt{0.2}+\sqrt{5}-\sqrt{180}\)

Hints

- Express every radical as a multiple of \(\sqrt{5}\). - Rewrite \(0.2\) as a fraction before simplifying its square root. - Rationalize the denominator if a simplified fraction still contains a radical there. - Combine the rational coefficients at the end.

Solution

1. Rewrite each term as a multiple of \(\sqrt{5}\): \(\sqrt{45}=3\sqrt{5}\), \(\sqrt{20}=2\sqrt{5}\), \(\sqrt{125}=5\sqrt{5}\), \(\sqrt{80}=4\sqrt{5}\), \(\sqrt{0.2}=\frac{\sqrt{5}}{5}\), and \(\sqrt{180}=6\sqrt{5}\). 2. Combine coefficients: \(3-2+5-4+\frac{1}{5}+1-6=-\frac{14}{5}\). 3. The simplified result is \(-\frac{14\sqrt{5}}{5}\).

Answer

\(-\frac{14\sqrt{5}}{5}\)
52485211
Simplify completely: \(\sqrt{18}-\sqrt{12}+\sqrt{0.5}-\sqrt{5\frac{1}{3}}+\sqrt{200}-\sqrt{108}\)

Hints

- Group terms according to the radicand that remains after simplification. - Convert the mixed number to an improper fraction. - Rationalize any denominator containing a radical. - Track the negative signs carefully.

Solution

1. The terms with \(\sqrt{2}\) become \(\sqrt{18}=3\sqrt{2}\), \(\sqrt{0.5}=\frac{\sqrt{2}}{2}\), and \(\sqrt{200}=10\sqrt{2}\). Their sum is \(\frac{27}{2}\sqrt{2}\). 2. The terms with \(\sqrt{3}\) become \(\sqrt{12}=2\sqrt{3}\), \(\sqrt{5\frac{1}{3}}=\sqrt{\frac{16}{3}}=\frac{4\sqrt{3}}{3}\), and \(\sqrt{108}=6\sqrt{3}\). Including the negative signs, their sum is \(-\frac{28}{3}\sqrt{3}\). 3. Therefore, the expression simplifies to \(\frac{27}{2}\sqrt{2}-\frac{28}{3}\sqrt{3}\).

Answer

\(\frac{27}{2}\sqrt{2}-\frac{28}{3}\sqrt{3}\)
52485511
Simplify the expression completely, given that \(x>y>0\) and \(z>0\): \(x\sqrt{z}+\sqrt{9x^2z}-\sqrt{4x^2z}+\sqrt{(x-y)^2}-\sqrt{(x+y)^2}\)

Hints

- Extract perfect-square factors from the radicals. - Use the relationship between the square root of a square and absolute value. - Use \(x>y\) to determine the sign of \(x-y\). - Combine terms with the same radical factor.

Solution

1. Since \(x>0\) and \(z>0\), \(\sqrt{9x^2z}=3x\sqrt{z}\) and \(\sqrt{4x^2z}=2x\sqrt{z}\). 2. Since \(x>y>0\), both \(x-y\) and \(x+y\) are positive. Thus, \(\sqrt{(x-y)^2}=x-y\) and \(\sqrt{(x+y)^2}=x+y\). 3. Substitute these results: \(x\sqrt{z}+3x\sqrt{z}-2x\sqrt{z}+(x-y)-(x+y)\). 4. Combine like terms: \((1+3-2)x\sqrt{z}=2x\sqrt{z}\) and \(x-y-x-y=-2y\). 5. The simplified expression is \(2x\sqrt{z}-2y\).

Answer

\(2x\sqrt{z}-2y\)
52485611
Simplify \(T=\sqrt{4a^2-8ab+4b^2}+\sqrt{a^2}-\sqrt{(a+b)^2}\), given that \(a>b>0\).

Hints

- Factor a common factor from the first radicand and look for a squared-binomial pattern. - Remember that the square root of a square is an absolute value. - Use \(a>b>0\) to determine the signs of the expressions inside the absolute values.

Solution

1. Factor the first radicand: \(4a^2-8ab+4b^2=4(a^2-2ab+b^2)=4(a-b)^2\). 2. Since \(a>b\), \(a-b>0\), so \(\sqrt{4(a-b)^2}=2(a-b)\). 3. Since \(a>0\) and \(a+b>0\), \(\sqrt{a^2}=a\) and \(\sqrt{(a+b)^2}=a+b\). 4. Therefore, \(T=2(a-b)+a-(a+b)\). 5. Combine like terms: \(T=2a-2b+a-a-b=2a-3b\).

Answer

\(2a-3b\)
52486211
Multiply and simplify. For part 2, assume \(x\ge0\) and \(y\ge0\). For part 3, assume \(a+b\ge0\) and \(a-b\ge0\). 1) \((5-2\sqrt{3})(5+2\sqrt{3})\) 2) \((x\sqrt{y}+y\sqrt{x})(x\sqrt{y}-y\sqrt{x})\) 3) \((2\sqrt{a+b}-\sqrt{a-b})(2\sqrt{a+b}+\sqrt{a-b})\)

Hints

- Identify the expressions that play the roles of \(u\) and \(v\) in \((u-v)(u+v)\). - Square every factor in a product such as \(2\sqrt{3}\). - Use parentheses when subtracting an entire squared expression.

Solution

1. Each product is a product of conjugates, so use \((u-v)(u+v)=u^2-v^2\). 2. For 1), \(5^2-(2\sqrt{3})^2=25-12=13\). 3. For 2), \((x\sqrt{y})^2-(y\sqrt{x})^2=x^2y-xy^2=xy(x-y)\). 4. For 3), \((2\sqrt{a+b})^2-(\sqrt{a-b})^2=4(a+b)-(a-b)=3a+5b\).

Answer

1) \(13\) 2) \(xy(x-y)\) 3) \(3a+5b\)
52486311
Evaluate without a calculator. \(A=(\sqrt[3]{49}+\sqrt[3]{14}+\sqrt[3]{4})(\sqrt[3]{7}-\sqrt[3]{2})\)

Hints

- Identify a difference-of-cubes identity. - Let the two simple cube roots represent new variables. - Match the three terms in the first factor to \(u^2\), \(uv\), and \(v^2\).

Solution

1. Let \(u=\sqrt[3]{7}\) and \(v=\sqrt[3]{2}\). Then the expression is \((u^2+uv+v^2)(u-v)\). 2. Use \((u^2+uv+v^2)(u-v)=u^3-v^3\). 3. Therefore \(A=7-2=5\).

Answer

\(A=5\)
52486511
For \(x\ge0\), simplify completely: \(T=(2\sqrt{18x}-5\sqrt{2x}+4)+(\sqrt{50x}-3\sqrt{8x})\)

Hints

- Extract perfect-square factors from \(18\), \(50\), and \(8\). - Rewrite every radical term with the same radicand. - Combine the coefficients of the like radical terms.

Solution

1. Simplify each radical term: \(2\sqrt{18x}=6\sqrt{2x}\), \(\sqrt{50x}=5\sqrt{2x}\), and \(3\sqrt{8x}=6\sqrt{2x}\). 2. Substitute these forms: \(T=(6\sqrt{2x}-5\sqrt{2x}+4)+(5\sqrt{2x}-6\sqrt{2x})\). 3. The radical coefficients add to \(6-5+5-6=0\), so all radical terms cancel and \(T=4\).

Answer

\(4\)
52486611
Determine whether the equation is true for every \(y\ge0\). Show your reasoning. \(\sqrt{27y}+\sqrt{48y}=\sqrt{147y}\)

Hints

- Extract the largest perfect-square factor from each radicand. - Rewrite all three radicals with a common radicand. - Compare the fully simplified expressions on the two sides.

Solution

1. Simplify the left side: \(\sqrt{27y}=3\sqrt{3y}\) and \(\sqrt{48y}=4\sqrt{3y}\), so \(\sqrt{27y}+\sqrt{48y}=7\sqrt{3y}\). 2. Simplify the right side: \(\sqrt{147y}=7\sqrt{3y}\). 3. Both sides simplify to the same expression for every \(y\ge0\), so the equation is true on the stated domain.

Answer

Yes. Both sides simplify to \(7\sqrt{3y}\), so the equation is true for every \(y\ge0\).
52487411
Use exponent properties to write each expression as a single radical. Assume all variables are positive. 1) \(\sqrt[3]{\sqrt b}\) 2) \(\sqrt{c\sqrt[3]{c}}\) 3) \(\sqrt[5]{d^2\sqrt d}\)

Hints

- Rewrite every radical as a rational exponent. - Work from the innermost radical outward. - Multiply exponents for a power raised to another power.

Solution

1. \(\sqrt[3]{\sqrt b}=b^{\frac12\cdot\frac13}=b^{\frac16}=\sqrt[6]{b}\). 2. \(\sqrt{c\sqrt[3]{c}}=(c\cdot c^{\frac13})^{\frac12}=c^{\frac23}=\sqrt[3]{c^2}\). 3. \(\sqrt[5]{d^2\sqrt d}=(d^{2+\frac12})^{\frac15}=d^{\frac12}=\sqrt d\).

Answer

1) \(\sqrt[6]{b}\) 2) \(\sqrt[3]{c^2}\) 3) \(\sqrt d\)
52487811
Evaluate or simplify each expression. Assume all variables are positive. 1) \(\frac{\sqrt[3]{250}}{\sqrt[3]{2}}\) 2) \(\frac{\sqrt[3]{54a^7}}{\sqrt[3]{2a}}\) 3) \(\frac{10\sqrt{0.2}}{2\sqrt5}\)

Hints

- Combine radicals with the same index in a quotient. - Subtract variable exponents after combining the radicands. - Simplify the numerical coefficient outside the radical separately.

Solution

1. \(\frac{\sqrt[3]{250}}{\sqrt[3]{2}}=\sqrt[3]{125}=5\). 2. \(\frac{\sqrt[3]{54a^7}}{\sqrt[3]{2a}}=\sqrt[3]{27a^6}=3a^2\). 3. \(\frac{10\sqrt{0.2}}{2\sqrt5}=5\sqrt{\frac{0.2}{5}}=5\sqrt{0.04}=1\).

Answer

1) \(5\) 2) \(3a^2\) 3) \(1\)
52488211
Factor each expression and simplify any radicals when possible. 1) \(5+\sqrt{5}\) 2) \(\sqrt{x^3}+\sqrt{x}\), for \(x\ge0\) 3) \(\sqrt{24}-\sqrt{12}\) 4) \(\frac{\sqrt{30}+\sqrt{20}}{\sqrt{5}}\)

Hints

- Rewrite a positive number as a product involving its square root when that creates a common factor. - Extract perfect-square variable factors from radicals. - Look for a common radical factor in a sum or difference. - In a fraction, check whether the numerator and denominator share a radical factor.

Solution

1. Write \(5=\sqrt{5}\cdot\sqrt{5}\), then factor: \(5+\sqrt{5}=\sqrt{5}(\sqrt{5}+1)\). 2. Since \(x\ge0\), \(\sqrt{x^3}=x\sqrt{x}\). Thus, \(x\sqrt{x}+\sqrt{x}=\sqrt{x}(x+1)\). 3. Factor out \(\sqrt{12}\): \(\sqrt{24}-\sqrt{12}=\sqrt{12}(\sqrt{2}-1)=2\sqrt{3}(\sqrt{2}-1)\). 4. Factor \(\sqrt{5}\) from the numerator: \(\frac{\sqrt{5}(\sqrt{6}+2)}{\sqrt{5}}=\sqrt{6}+2\).

Answer

1) \(\sqrt{5}(\sqrt{5}+1)\) 2) \(\sqrt{x}(x+1)\) 3) \(2\sqrt{3}(\sqrt{2}-1)\) 4) \(\sqrt{6}+2\)
52488611
Simplify each expression completely for positive \(x\), \(a\), and \(b\). 1) \(\frac{\sqrt{x^3}+\sqrt{x}}{\sqrt{1/x}}\) 2) \(\frac{\sqrt{a^2b}-\sqrt{b^3}}{\sqrt{b/a^2}}\)

Hints

- Replace division by a radical with multiplication by its reciprocal. - Distribute the reciprocal radical across the numerator. - Combine products of radicals and simplify their radicands. - Use the fact that all variables are positive when taking square roots of squares.

Solution

1. Dividing by \(\sqrt{1/x}\) is equivalent to multiplying by \(\sqrt{x}\). Therefore, \((\sqrt{x^3}+\sqrt{x})\sqrt{x}=\sqrt{x^4}+\sqrt{x^2}=x^2+x\). 2. Dividing by \(\sqrt{b/a^2}\) is equivalent to multiplying by \(\sqrt{a^2/b}\). Thus, \((\sqrt{a^2b}-\sqrt{b^3})\sqrt{\frac{a^2}{b}}=\sqrt{a^4}-\sqrt{a^2b^2}=a^2-ab\).

Answer

1) \(x^2+x\) 2) \(a^2-ab\)
52489011
Factor each expression as far as possible using radical properties and algebraic identities. Assume \(a\geq2\), \(x\geq0\), and \(y\geq0\). 1) \(\sqrt{a^2-4}-\sqrt{a+2}\) 2) \(\sqrt[3]{x^2}-\sqrt[3]{y^2}\) 3) \(z\sqrt z-z\), for \(z\geq0\)

Hints

- Look for a difference of squares inside or outside a radical. - Rewrite cube roots with exponent \(\frac13\) if that reveals a familiar identity. - Identify the greatest common factor in part 3.

Solution

1. Since \(a^2-4=(a-2)(a+2)\), \(\sqrt{a^2-4}-\sqrt{a+2}=\sqrt{a+2}(\sqrt{a-2}-1)\). 2. View the expression as a difference of squares: \((\sqrt[3]{x})^2-(\sqrt[3]{y})^2=(\sqrt[3]{x}-\sqrt[3]{y})(\sqrt[3]{x}+\sqrt[3]{y})\). 3. Factor out \(z\): \(z\sqrt z-z=z(\sqrt z-1)\).

Answer

1) \(\sqrt{a+2}(\sqrt{a-2}-1)\) 2) \((\sqrt[3]{x}-\sqrt[3]{y})(\sqrt[3]{x}+\sqrt[3]{y})\) 3) \(z(\sqrt z-1)\)
52489111
Let \(T=(6\sqrt{28}-2\sqrt{63}+\sqrt{112})\div\sqrt{7}\). a) Find \(T\) by distributing the division and dividing each term by \(\sqrt{7}\). b) Find \(T\) again by simplifying and combining the radicals inside the parentheses before dividing. c) Explain why both methods must give the same result.

Hints

- Use the quotient property for square roots. - Simplify each radicand by extracting a factor of \(7\). - Division by a common nonzero factor distributes across a sum or difference. - Check what happens when the same nonzero radical factor appears in the numerator and denominator.

Solution

1. Distributing the division gives \(6\sqrt{4}-2\sqrt{9}+\sqrt{16}=12-6+4=10\). 2. Alternatively, \(\sqrt{28}=2\sqrt{7}\), \(\sqrt{63}=3\sqrt{7}\), and \(\sqrt{112}=4\sqrt{7}\). The numerator becomes \(12\sqrt{7}-6\sqrt{7}+4\sqrt{7}=10\sqrt{7}\), and \(10\sqrt{7}\div\sqrt{7}=10\). 3. Both methods apply equivalent algebraic and radical properties to the same expression, so they preserve its value.

Answer

a) \(10\) b) \(10\) c) Both methods use valid equivalent transformations of the same expression.
52489211
Simplify the expression, then determine whether the result is a natural number. \(\frac{\frac12\sqrt[3]{16}+\frac13\sqrt[3]{54}-\sqrt[3]{2}}{\sqrt[3]{2}}\)

Hints

- Divide every numerator term by the denominator. - Combine cube roots in each quotient. - Evaluate the resulting perfect cubes.

Solution

1. Divide each term in the numerator by \(\sqrt[3]{2}\): \(\frac12\sqrt[3]{8}+\frac13\sqrt[3]{27}-\sqrt[3]{1}\). 2. Evaluate the cube roots: \(\frac12\cdot2+\frac13\cdot3-1=1\). 3. The result \(1\) is a natural number.

Answer

\(1\), which is a natural number.
52490011
Simplify each fraction by factoring the numerator and canceling a common factor. 1) \(\frac{\sqrt{7}+7}{\sqrt{7}}\) 2) \(\frac{a-\sqrt{a}}{\sqrt{a}-1}\), for \(a>0\) and \(a\ne1\) 3) \(\frac{\sqrt{15}-\sqrt{5}}{\sqrt{5}}\)

Hints

- Rewrite the numerator to expose a factor that also appears in the denominator. - Express a nonnegative variable as a product of two equal square roots. - Use the product property to rewrite \(\sqrt{15}\). - Confirm that any canceled factor is nonzero.

Solution

1. Factor \(\sqrt{7}\) from the numerator: \(\frac{\sqrt{7}(1+\sqrt{7})}{\sqrt{7}}=1+\sqrt{7}\). 2. Since \(a=\sqrt{a}\cdot\sqrt{a}\), factor the numerator: \(\frac{\sqrt{a}(\sqrt{a}-1)}{\sqrt{a}-1}=\sqrt{a}\). The condition \(a\ne1\) ensures the canceled factor is nonzero. 3. Rewrite \(\sqrt{15}=\sqrt{5}\sqrt{3}\), then factor and cancel: \(\frac{\sqrt{5}(\sqrt{3}-1)}{\sqrt{5}}=\sqrt{3}-1\).

Answer

1) \(1+\sqrt{7}\) 2) \(\sqrt{a}\) 3) \(\sqrt{3}-1\)
52490311
Factor each expression completely. Assume \(u,v,x,y\ge0\). 1) \(\sqrt{uv}-\sqrt{3u}+\sqrt{2v}-\sqrt{6}\) 2) \(x-y-3\sqrt{x}+3\sqrt{y}\)

Hints

- Group terms in pairs that have a common radical factor. - After factoring each group, look for a common binomial. - Rewrite a difference of nonnegative variables as a difference of squares involving their square roots. - Treat \(x\) and \(y\) as \((\sqrt{x})^2\) and \((\sqrt{y})^2\).

Solution

1. Group the first two and last two terms: \((\sqrt{uv}-\sqrt{3u})+(\sqrt{2v}-\sqrt{6})\). Factor each group to get \(\sqrt{u}(\sqrt{v}-\sqrt{3})+\sqrt{2}(\sqrt{v}-\sqrt{3})\). Factoring the common binomial gives \((\sqrt{u}+\sqrt{2})(\sqrt{v}-\sqrt{3})\). 2. Rewrite \(x-y=(\sqrt{x}-\sqrt{y})(\sqrt{x}+\sqrt{y})\), and rewrite \(-3\sqrt{x}+3\sqrt{y}=-3(\sqrt{x}-\sqrt{y})\). Factoring the common binomial gives \((\sqrt{x}-\sqrt{y})(\sqrt{x}+\sqrt{y}-3)\).

Answer

1) \((\sqrt{u}+\sqrt{2})(\sqrt{v}-\sqrt{3})\) 2) \((\sqrt{x}-\sqrt{y})(\sqrt{x}+\sqrt{y}-3)\)
52490611
Factor each expression by extracting a common radical factor. 1) \(\sqrt{x^2-16}+x-4\), for \(x\ge4\) 2) \(\sqrt{x^2-2xy+y^2}+\sqrt{x-y}\), for \(x\ge y\)

Hints

- Factor expressions under the radicals when possible. - Rewrite a nonnegative expression without a radical as the square of its square root. - In part 2, recognize a perfect-square trinomial under the first radical.

Solution

1. Factor \(x^2-16=(x-4)(x+4)\), and write \(x-4=(\sqrt{x-4})^2\). Then \(\sqrt{x^2-16}+x-4=\sqrt{x-4}\sqrt{x+4}+(\sqrt{x-4})^2\), so the factored form is \(\sqrt{x-4}(\sqrt{x+4}+\sqrt{x-4})\). 2. Since \(x^2-2xy+y^2=(x-y)^2\) and \(x-y\ge0\), the first term is \(x-y\). Thus, \((x-y)+\sqrt{x-y}=\sqrt{x-y}(\sqrt{x-y}+1)\).

Answer

1) \(\sqrt{x-4}(\sqrt{x+4}+\sqrt{x-4})\) 2) \(\sqrt{x-y}(\sqrt{x-y}+1)\)
52492411
Simplify each expression as far as possible. Assume all variables are positive. a) \((\sqrt[4]{a^3})^2\) b) \((-\sqrt[3]{b^2})^4\) c) \(\left(-\frac23\sqrt[5]{x^3}\right)^3\)

Hints

- Rewrite radicals as rational exponents. - Apply the outer power to the coefficient and radical factor. - Separate any whole-number part of the resulting exponent.

Solution

1. \((\sqrt[4]{a^3})^2=a^{\frac32}=a\sqrt a\). 2. \((-\sqrt[3]{b^2})^4=b^{\frac83}=b^2\sqrt[3]{b^2}\). 3. \(\left(-\frac23\sqrt[5]{x^3}\right)^3=-\frac8{27}x^{\frac95}=-\frac8{27}x\sqrt[5]{x^4}\).

Answer

a) \(a\sqrt a\) b) \(b^2\sqrt[3]{b^2}\) c) \(-\frac8{27}x\sqrt[5]{x^4}\)
52493611
Simplify completely: \((4-3\sqrt{3})^2+\sqrt{1728}\)

Hints

- Expand the squared binomial first. - Factor a large perfect square from \(1728\). - Check whether the radical terms cancel.

Solution

1. Expanding gives \((4-3\sqrt{3})^2=16-24\sqrt{3}+27=43-24\sqrt{3}\). 2. Since \(1728=576\cdot3\), \(\sqrt{1728}=24\sqrt{3}\). 3. The radical terms cancel: \(43-24\sqrt{3}+24\sqrt{3}=43\).

Answer

\(43\)
52494211
Let \(A=\left(\frac{a}{3b}\sqrt[4]{\frac{27b^3}{a}}\right)^2\) and \(B=\frac{a\sqrt{3ab}}{3b}\), where \(a>0\) and \(b>0\). Simplify \(A\) step by step and determine whether \(A=B\).

Hints

- Squaring a fourth root produces a square root. - Extract perfect-square factors from the radical. - Rationalize the remaining square-root denominator before comparing with \(B\).

Solution

1. Square the factors: \(A=\frac{a^2}{9b^2}\sqrt{\frac{27b^3}{a}}\). 2. Simplify the square root: \(\sqrt{\frac{27b^3}{a}}=\frac{3b\sqrt{3b}}{\sqrt a}\). 3. Then \(A=\frac{a^2\sqrt{3b}}{3b\sqrt a}\). 4. Multiply numerator and denominator by \(\sqrt a\): \(A=\frac{a^2\sqrt{3ab}}{3ab}=\frac{a\sqrt{3ab}}{3b}=B\).

Answer

Yes. \(A=B=\frac{a\sqrt{3ab}}{3b}\).
52494611
Expand and simplify each expression. Assume all variables are positive. a) \((5\sqrt{z}-1)^2\) b) \(\left(\frac{1}{2}\sqrt{x}+4\sqrt{y}\right)^2\) c) \((\sqrt{xy}-3\sqrt{x})^2\)

Hints

- Apply the square-of-a-binomial identities before simplifying. - Square both the coefficient and the radical in each first and last term. - In c), combine the product \(\sqrt{xy}\sqrt{x}\) under one radical and extract the perfect-square factor.

Solution

1. In a), use \((u-v)^2=u^2-2uv+v^2\): \((5\sqrt{z})^2-2(5\sqrt{z})(1)+1^2=25z-10\sqrt{z}+1\). 2. In b), use \((u+v)^2=u^2+2uv+v^2\): \(\left(\frac{1}{2}\sqrt{x}\right)^2+2\left(\frac{1}{2}\sqrt{x}\right)(4\sqrt{y})+(4\sqrt{y})^2=\frac{x}{4}+4\sqrt{xy}+16y\). 3. In c), expand: \((\sqrt{xy})^2-2(\sqrt{xy})(3\sqrt{x})+(3\sqrt{x})^2\). Because \(x>0\), \(\sqrt{xy}\sqrt{x}=x\sqrt{y}\). The result is \(xy-6x\sqrt{y}+9x\).

Answer

a) \(25z-10\sqrt{z}+1\) b) \(\frac{x}{4}+4\sqrt{xy}+16y\) c) \(xy-6x\sqrt{y}+9x\)
52495311
Work with radical expressions and binomial formulas. a) Evaluate \((\sqrt{7}+2\sqrt{7})^2\) in two ways: first combine like radicals, and then use the square-of-a-sum formula. b) Simplify \((\sqrt{32}-3\sqrt{2})^2\) by simplifying the radicals before squaring. c) A student claims, “\((\sqrt{a}+\sqrt{b})^2=a+b\).” Test the claim with an example and identify the missing term.

Hints

- Combine like radicals as you would like terms. - Simplify \(\sqrt{32}\) before squaring. - Use \((x+y)^2=x^2+2xy+y^2\). - Test a simple numerical case before accepting a statement as universally true.

Solution

1. Combining first gives \((3\sqrt{7})^2=63\). Expanding instead gives \(7+2(\sqrt{7})(2\sqrt{7})+28=7+28+28=63\). 2. Since \(\sqrt{32}=4\sqrt{2}\), \((\sqrt{32}-3\sqrt{2})^2=(\sqrt{2})^2=2\). 3. For example, with \(a=b=1\), \((\sqrt{1}+\sqrt{1})^2=4\), while \(a+b=2\). The claim omits the cross term \(2\sqrt{ab}\).

Answer

a) \(63\) b) \(2\) c) The claim is false; the missing term is \(2\sqrt{ab}\).
52495411
Complete each radical-expression task. a) Evaluate \(\left(\frac{1}{2}\sqrt{12}+\sqrt{3}\right)^2\). Simplify inside the parentheses first. b) Expand and simplify \((3\sqrt{5}-2\sqrt{3})^2\). c) Verify by squaring the right side that \(\sqrt{7+4\sqrt{3}}=2+\sqrt{3}\).

Hints

- Extract perfect-square factors before squaring. - Apply the square-of-a-difference formula carefully. - To verify \(\sqrt{A}=B\), check both \(B^2=A\) and \(B\ge0\).

Solution

1. Since \(\sqrt{12}=2\sqrt{3}\), \(\left(\frac{1}{2}\sqrt{12}+\sqrt{3}\right)^2=(2\sqrt{3})^2=12\). 2. \((3\sqrt{5}-2\sqrt{3})^2=45-12\sqrt{15}+12=57-12\sqrt{15}\). 3. \((2+\sqrt{3})^2=4+4\sqrt{3}+3=7+4\sqrt{3}\). Also, \(2+\sqrt{3}>0\), so it is the principal square root of \(7+4\sqrt{3}\).

Answer

a) \(12\) b) \(57-12\sqrt{15}\) c) \((2+\sqrt{3})^2=7+4\sqrt{3}\) and \(2+\sqrt{3}>0\).
52495911
Find the exact value of each expression using binomial formulas. a) \((\sqrt{9+\sqrt{17}}+\sqrt{9-\sqrt{17}})^2\) b) \((\sqrt{10-2\sqrt{21}}-\sqrt{10+2\sqrt{21}})^2\)

Hints

- Expand each squared binomial. - Recall that squaring a square root returns its nonnegative radicand. - Simplify the product of conjugate expressions using a difference of squares. - Look for radical terms that cancel.

Solution

1. For a), expanding gives \(9+\sqrt{17}+9-\sqrt{17}+2\sqrt{(9+\sqrt{17})(9-\sqrt{17})}\). 2. The product is \(81-17=64\), so the expression equals \(18+2\sqrt{64}=18+16=34\). 3. For b), expanding gives \(10-2\sqrt{21}+10+2\sqrt{21}-2\sqrt{(10-2\sqrt{21})(10+2\sqrt{21})}\). 4. The product is \(100-84=16\), so the expression equals \(20-2\sqrt{16}=20-8=12\).

Answer

a) \(34\) b) \(12\)
52496011
Let \(T=\frac{1}{4}(\sqrt{11+\sqrt{72}}+\sqrt{11-\sqrt{72}})^2\). Show by calculation that \(T\) is a perfect square.

Hints

- Expand the large squared sum first. - Use a difference of squares for the product inside the cross term. - Recall the definition of a perfect square. - Check whether the final value is the square of an integer.

Solution

1. Expanding the squared sum gives \(11+\sqrt{72}+11-\sqrt{72}+2\sqrt{(11+\sqrt{72})(11-\sqrt{72})}\). 2. The conjugate product is \(121-72=49\), so the squared sum equals \(22+2\sqrt{49}=22+14=36\). 3. Therefore, \(T=\frac{1}{4}\cdot36=9=3^2\), which is a perfect square.

Answer

\(T=9=3^2\), so the value is a perfect square.
52496111
Expand each square and simplify completely. a) \((\sqrt{7}+\sqrt{3}+2)^2\) b) \((2\sqrt{5}-\sqrt{20}+\sqrt{2})^2\)

Hints

- Simplify inside the parentheses before expanding when possible. - For three terms, include every square and each pairwise cross product twice. - Combine like radicals before squaring. - Simplify each radical enough to identify all like radical terms.

Solution

1. For a), squaring the three-term sum gives \(7+3+4+2\sqrt{21}+4\sqrt{7}+4\sqrt{3}\). Therefore, the result is \(14+2\sqrt{21}+4\sqrt{7}+4\sqrt{3}\). 2. For b), \(\sqrt{20}=2\sqrt{5}\), so the expression inside the parentheses simplifies to \(\sqrt{2}\). Its square is \(2\).

Answer

a) \(14+2\sqrt{21}+4\sqrt{7}+4\sqrt{3}\) b) \(2\)
52496211
Complete each radical-expression task. a) Evaluate \((\sqrt{12}+\sqrt{3}-\sqrt{2})^2\). Simplify inside the parentheses first. b) Show by calculation that \((\sqrt{2}+\sqrt{8}+\sqrt{32})^2\) is a natural number.

Hints

- Simplify the radicals before squaring. - Combine like radicals inside each set of parentheses. - Apply the square-of-a-difference formula carefully. - Check whether the radical terms cancel so the result is a natural number.

Solution

1. Since \(\sqrt{12}=2\sqrt{3}\), the first expression becomes \((3\sqrt{3}-\sqrt{2})^2=27-6\sqrt{6}+2=29-6\sqrt{6}\). 2. Since \(\sqrt{8}=2\sqrt{2}\) and \(\sqrt{32}=4\sqrt{2}\), the second expression becomes \((7\sqrt{2})^2=98\), which is a natural number.

Answer

a) \(29-6\sqrt{6}\) b) \(98\), a natural number
52496311
Use binomial formulas with radical expressions. 1. Expand and simplify \((\sqrt{5}+\sqrt{2})^2\). 2. Use a binomial formula in reverse to simplify \(\sqrt{7-2\sqrt{10}}\). 3. Similarly, simplify \(\sqrt{12+2\sqrt{35}}\).

Hints

- Use \((a\pm b)^2=a^2\pm2ab+b^2\). - Look for two numbers whose sum and product match the nonradical and radical parts. - Try expressing the large radicand as the square of a binomial. - Verify that the simplified expression is nonnegative.

Solution

1. \((\sqrt{5}+\sqrt{2})^2=5+2\sqrt{10}+2=7+2\sqrt{10}\). 2. Since \((\sqrt{5}-\sqrt{2})^2=7-2\sqrt{10}\) and \(\sqrt{5}-\sqrt{2}>0\), \(\sqrt{7-2\sqrt{10}}=\sqrt{5}-\sqrt{2}\). 3. The numbers \(7\) and \(5\) have sum \(12\) and product \(35\). Thus, \((\sqrt{7}+\sqrt{5})^2=12+2\sqrt{35}\), so \(\sqrt{12+2\sqrt{35}}=\sqrt{7}+\sqrt{5}\).

Answer

1. \(7+2\sqrt{10}\) 2. \(\sqrt{5}-\sqrt{2}\) 3. \(\sqrt{7}+\sqrt{5}\)
52497111
Explore nested radicals. a) Evaluate \(\sqrt{\sqrt{625}}\) and \(\sqrt[4]{625}\). What do you notice? b) Use rational exponents to explain why \(\sqrt{\sqrt a}=\sqrt[4]{a}\) for \(a\geq0\). c) Find the natural number \(n\geq2\) that satisfies \(\sqrt[3]{\sqrt[n]{729}}=3\).

Hints

- Rewrite each radical as a rational exponent. - Multiply exponents for nested powers. - Write \(729\) as a power of \(3\).

Solution

1. \(\sqrt{\sqrt{625}}=\sqrt{25}=5\), and \(\sqrt[4]{625}=5\). The values are equal. 2. \(\sqrt{\sqrt a}=(a^{\frac12})^{\frac12}=a^{\frac14}=\sqrt[4]{a}\). 3. Since \(729=3^6\), \(\sqrt[3]{\sqrt[n]{729}}=3^{\frac6{3n}}=3\). Thus \(\frac6{3n}=1\), so \(n=2\).

Answer

a) Both values are \(5\). b) \(\sqrt{\sqrt a}=a^{\frac14}=\sqrt[4]{a}\). c) \(n=2\)
52497211
Complete each task involving nested radicals. a) Compare \(A=\sqrt[3]{\sqrt{4096}}\) and \(B=\sqrt{\sqrt{\sqrt{256}}}\sqrt[3]{8}\). b) Simplify \(\frac{\sqrt[4]{\sqrt{x^{16}}}}{\sqrt x}\) for \(x>0\).

Hints

- Multiply radical indices when roots are nested. - Write the numerical radicands as powers of \(2\). - Subtract exponents when dividing powers of \(x\).

Solution

1. \(A=\sqrt[6]{4096}=\sqrt[6]{2^{12}}=4\). 2. \(B=\sqrt[8]{256}\cdot2=\sqrt[8]{2^8}\cdot2=4\). Thus \(A=B\). 3. \(\sqrt[4]{\sqrt{x^{16}}}=x^2\). Therefore \(\frac{x^2}{x^{\frac12}}=x^{\frac32}=x\sqrt x\).

Answer

a) \(A=B=4\) b) \(x\sqrt x\)
52497611
Let \(A=\sqrt[3]{2\sqrt2}\) and \(B=\sqrt[4]{2\sqrt[3]{2}}\). Determine which value is greater by rewriting each expression as a single radical.

Hints

- Rewrite inner radicals as rational exponents. - Combine powers with base \(2\). - For a base greater than \(1\), compare the resulting exponents.

Solution

1. \(A=(2\cdot2^{\frac12})^{\frac13}=2^{\frac12}=\sqrt2\). 2. \(B=(2\cdot2^{\frac13})^{\frac14}=2^{\frac13}=\sqrt[3]{2}\). 3. Since \(2>1\) and \(\frac12>\frac13\), \(2^{\frac12}>2^{\frac13}\). Therefore \(A>B\).

Answer

\(A>B\), because \(A=\sqrt2\) and \(B=\sqrt[3]{2}\).
52504311
Let \(x=\frac{\sqrt{a}+\sqrt{b}}{\sqrt{a}}\) and \(y=\frac{\sqrt{a}-\sqrt{b}}{\sqrt{a}}\), where \(a,b>0\). Find \(T=\frac{x+y}{x-y}\) in terms of \(a\) and \(b\), and simplify completely.

Hints

- Compute \(x+y\) and \(x-y\) separately first. - Combine fractions that have the same denominator. - Dividing by a fraction is equivalent to multiplying by its reciprocal.

Solution

1. Add the given expressions: \(x+y=\frac{\sqrt{a}+\sqrt{b}+\sqrt{a}-\sqrt{b}}{\sqrt{a}}=2\). 2. Subtract them: \(x-y=\frac{\sqrt{a}+\sqrt{b}-(\sqrt{a}-\sqrt{b})}{\sqrt{a}}=\frac{2\sqrt{b}}{\sqrt{a}}\). 3. Therefore, \(T=\frac{2}{2\sqrt{b}/\sqrt{a}}=\frac{\sqrt{a}}{\sqrt{b}}=\sqrt{\frac{a}{b}}\).

Answer

\(T=\sqrt{\frac{a}{b}}\)
52506111
Simplify completely: \(\frac{\sqrt{x^2-4}}{x-\sqrt{x^2-4}}\), where \(x=a+\frac{1}{a}\) and \(a>1\).

Hints

- Substitute for \(x\) inside the radicand and expand. - Look for a perfect-square expression involving \(a\) and \(1/a\). - Use \(a>1\) when taking the square root. - Simplify the numerator and denominator before dividing.

Solution

1. Substitute for \(x\): \(x^2-4=\left(a+\frac{1}{a}\right)^2-4=a^2-2+\frac{1}{a^2}=\left(a-\frac{1}{a}\right)^2\). 2. Since \(a>1\), \(a-\frac{1}{a}>0\), so \(\sqrt{x^2-4}=a-\frac{1}{a}\). 3. The denominator becomes \(a+\frac{1}{a}-\left(a-\frac{1}{a}\right)=\frac{2}{a}\). 4. Thus, \(\frac{a-1/a}{2/a}=\frac{a^2-1}{2}\).

Answer

\(\frac{a^2-1}{2}\)
52537511
Find all real solutions: \(\frac{4}{\sqrt{x^2+8}-x}-\frac{4}{\sqrt{x^2+8}+x}=x^2\).

Hints

- Use a common denominator on the left side. - The denominator is a product of conjugates. - Simplify completely before solving the resulting polynomial equation.

Solution

1. Since \(x^2+8>0\) and \(\sqrt{x^2+8}>|x|\), neither denominator is zero. The domain is all real numbers. 2. Combine the fractions. The common denominator is \((\sqrt{x^2+8}-x)(\sqrt{x^2+8}+x)=x^2+8-x^2=8\). 3. The combined numerator is \(4(\sqrt{x^2+8}+x)-4(\sqrt{x^2+8}-x)=8x\). 4. The equation simplifies to \(\frac{8x}{8}=x^2\), or \(x=x^2\). 5. Factor: \(x(x-1)=0\). Thus \(x=0\) or \(x=1\), and both satisfy the original equation.

Answer

\(\{0,1\}\)
52704211
Complete each task. a) Which value is greater: \(2\sqrt[4]{3}\) or \(\sqrt[4]{50}\)? Justify your answer by moving the coefficient into the radical. b) Simplify \(\sqrt[3]{x\sqrt x}\) for \(x\geq0\).

Hints

- Raise the outside coefficient to the fourth power before moving it inside. - Rewrite the nested radical using rational exponents. - Compare radicands once the radical indices match.

Solution

1. \(2\sqrt[4]{3}=\sqrt[4]{2^4\cdot3}=\sqrt[4]{48}\). Since \(48<50\), \(\sqrt[4]{50}\) is greater. 2. \(\sqrt[3]{x\sqrt x}=\left(x\cdot x^{\frac12}\right)^{\frac13}=x^{\frac12}=\sqrt x\).

Answer

a) \(\sqrt[4]{50}\) is greater. b) \(\sqrt x\)
52808611
Order \(2\sqrt{11}\), \(3\sqrt{5}\), and \(6.5\) from least to greatest. Justify your order by comparing their squares.

Hints

- Square each positive value. - Compare the resulting rational numbers. - Squaring preserves the order of positive numbers.

Solution

1. The squares are \((2\sqrt{11})^2=44\), \((3\sqrt{5})^2=45\), and \(6.5^2=42.25\). 2. Since all three values are positive and \(42.25<44<45\), the original values satisfy \(6.5<2\sqrt{11}<3\sqrt{5}\).

Answer

\(6.5<2\sqrt{11}<3\sqrt{5}\)
52809011
Compare each pair by first rewriting the values in the form \(\sqrt{n}\) without a calculator. Then verify your result by approximating each value to the nearest hundredth. a) \(3\sqrt{11}\) and \(10\) b) \(5\sqrt{6}\) and \(6\sqrt{5}\)

Hints

- Move a positive coefficient under the radical by squaring it. - Rewrite a positive integer as the square root of its square when useful. - Compare the radicands before calculating decimal approximations.

Solution

1. In a), \(3\sqrt{11}=\sqrt{99}\), while \(10=\sqrt{100}\). Therefore, \(3\sqrt{11}<10\). Numerically, \(3\sqrt{11}\approx9.95<10\). 2. In b), \(5\sqrt{6}=\sqrt{150}\) and \(6\sqrt{5}=\sqrt{180}\). Therefore, \(5\sqrt{6}<6\sqrt{5}\). Numerically, \(5\sqrt{6}\approx12.25\) and \(6\sqrt{5}\approx13.42\).

Answer

a) \(3\sqrt{11}<10\); approximately \(9.95<10\) b) \(5\sqrt{6}<6\sqrt{5}\); approximately \(12.25<13.42\)
52809411
Two radical terms are like terms when their fully simplified forms have the same radical index and radicand. Determine whether each pair is like. a) \(\sqrt[3]{24}\) and \(\sqrt[3]{81}\) b) \(\sqrt{12}\) and \(\sqrt[3]{12}\) c) \(\frac35\sqrt[3]{250}\) and \(0.5\sqrt[3]{128}\)

Hints

- Extract perfect cubes or squares first. - Compare both the radical index and the remaining radicand. - Coefficients do not have to match for terms to be like.

Solution

1. \(\sqrt[3]{24}=2\sqrt[3]{3}\), and \(\sqrt[3]{81}=3\sqrt[3]{3}\). They are like terms. 2. \(\sqrt{12}=2\sqrt3\) has index \(2\), while \(\sqrt[3]{12}\) has index \(3\). They are not like terms. 3. \(\frac35\sqrt[3]{250}=3\sqrt[3]{2}\), and \(0.5\sqrt[3]{128}=2\sqrt[3]{2}\). They are like terms.

Answer

a) Like terms b) Not like terms c) Like terms
52809811
Simplify each expression using radical properties. Then approximate the result to the nearest hundredth. 1) \(\frac{\sqrt{72}}{\sqrt{3}\cdot\sqrt{2}}\) 2) \(\sqrt{\frac{3}{4}}\cdot\sqrt{8}\) 3) \(\frac{\sqrt{5.4}}{\sqrt{0.3}}\) 4) \(\frac{\sqrt{14}\cdot\sqrt{2}}{\sqrt{4}}\)

Hints

- Combine products and quotients of square roots into a single radical. - Simplify inside the radical before taking a decimal approximation. - Keep track of the decimal point when dividing inside the radical. - Use the thousandths digit to round to the nearest hundredth.

Solution

1. \(\frac{\sqrt{72}}{\sqrt{3}\sqrt{2}}=\sqrt{\frac{72}{6}}=\sqrt{12}=2\sqrt{3}\approx3.46\). 2. \(\sqrt{\frac{3}{4}}\sqrt{8}=\sqrt{6}\approx2.45\). 3. \(\frac{\sqrt{5.4}}{\sqrt{0.3}}=\sqrt{18}=3\sqrt{2}\approx4.24\). 4. \(\frac{\sqrt{14}\sqrt{2}}{\sqrt{4}}=\sqrt{\frac{28}{4}}=\sqrt{7}\approx2.65\).

Answer

1) \(2\sqrt{3}\approx3.46\) 2) \(\sqrt{6}\approx2.45\) 3) \(3\sqrt{2}\approx4.24\) 4) \(\sqrt{7}\approx2.65\)
53501411
Let \(f(x)=\sqrt{x^2-2x+5}\). Use the expression under the radical to find the range of \(f\), and justify your answer algebraically.
Figure for problem 535014

Hints

- Complete the square in the radicand. - Find the smallest possible value under the square root. - Use the fact that the square-root function is increasing.

Solution

1. Complete the square in the radicand: \(x^2-2x+5=(x-1)^2+4\). 2. Since \((x-1)^2\ge0\), the radicand has a minimum value of \(4\), reached at \(x=1\). 3. The square-root function is increasing on nonnegative inputs, so the minimum value of \(f\) is \(\sqrt{4}=2\). 4. As \(|x|\to\infty\), the radicand and therefore \(f(x)\) increase without bound. Thus, every value at least \(2\) occurs.

Answer

\([2, \infty)\)
51436711
Investigate the relationship between a sum of square roots and the square root of a sum. a) Test \(\sqrt{a}+\sqrt{b}=\sqrt{a+b}\) for \(a=9\) and \(b=16\). b) A student conjectures that the equation is false for all positive numbers \(a\) and \(b\). Confirm or refute the conjecture by squaring both sides.

Hints

- Evaluate each side separately for the given values. - Expand \((x+y)^2\). - Compare the squared expressions and use the fact that both original sides are positive.

Solution

1. For a), \(\sqrt{9}+\sqrt{16}=3+4=7\), while \(\sqrt{9+16}=\sqrt{25}=5\). The equation is false for these values. 2. For positive \(a\) and \(b\), \((\sqrt{a}+\sqrt{b})^2=a+b+2\sqrt{ab}\). 3. Also, \((\sqrt{a+b})^2=a+b\). 4. Since \(a>0\) and \(b>0\), \(2\sqrt{ab}>0\). Therefore, \((\sqrt{a}+\sqrt{b})^2>(\sqrt{a+b})^2\). Both original expressions are positive, so \(\sqrt{a}+\sqrt{b}>\sqrt{a+b}\). 5. Thus, the student's conjecture is correct for all positive \(a\) and \(b\).

Answer

a) The equation is false because \(7\ne5\). b) The conjecture is correct. For \(a,b>0\), squaring gives \(a+b+2\sqrt{ab}>a+b\), so \(\sqrt{a}+\sqrt{b}>\sqrt{a+b}\).
52468511
For real numbers \(a\) and \(b\), determine the conditions under which both sides of each equation are defined and the equation is true. 1) \(\sqrt{ab}=\sqrt{-a}\cdot\sqrt{-b}\) 2) \(\sqrt{\frac{a}{b}}=\frac{\sqrt{-a}}{\sqrt{-b}}\)

Hints

- A real square root requires a nonnegative radicand. - A denominator cannot equal zero. - A minus sign before a variable does not by itself determine the sign of its value. - Determine the signs of the product or quotient after imposing the domain restrictions.

Solution

1. For \(\sqrt{-a}\) and \(\sqrt{-b}\) to be real, \(a\le0\) and \(b\le0\). Then \(ab\ge0\), so the left side is also defined. Under these conditions, \(\sqrt{-a}\cdot\sqrt{-b}=\sqrt{(-a)(-b)}=\sqrt{ab}\). 2. The numerator requires \(a\le0\). The denominator requires \(-b>0\), so \(b<0\). Then \(\frac{a}{b}\ge0\), and \(\frac{\sqrt{-a}}{\sqrt{-b}}=\sqrt{\frac{-a}{-b}}=\sqrt{\frac{a}{b}}\).

Answer

1) \(a\le0\) and \(b\le0\) 2) \(a\le0\) and \(b<0\)
52469511
Let \(T=\sqrt{\frac{a^5}{b^4}-\frac{a^4}{b^4}}\). a) Simplify \(T\) as much as possible. b) Find all real values of \(a\) and \(b\) for which \(T\) is defined.

Hints

- Combine the fractions and factor the numerator under the radical. - Enforce both the nonnegative-radicand condition and the nonzero-denominator condition. - Check separately whether a factor that is usually positive can equal zero. - Extract the fourth powers from the square root.

Solution

1. Combine and factor the terms under the radical: \(T=\sqrt{\frac{a^5-a^4}{b^4}}=\sqrt{\frac{a^4(a-1)}{b^4}}\). 2. The denominator requires \(b\ne0\). Because \(a^4\ge0\), the radicand is nonnegative when \(a=0\) or \(a-1\ge0\). Thus, \(a\in\{0\}\cup[1,\infty)\). 3. For \(a\ge1\), \(T=\sqrt{\frac{a^4}{b^4}}\sqrt{a-1}=\frac{a^2}{b^2}\sqrt{a-1}\). 4. When \(a=0\), the original radicand is \(0\), so \(T=0\).

Answer

a) For \(a\ge1\), \(T=\frac{a^2}{b^2}\sqrt{a-1}\); for \(a=0\), \(T=0\). b) \(a\in\{0\}\cup[1,\infty)\) and \(b\ne0\)
52472411
Check each transformation. a) Move the outside factor in \(\frac{k}{2}\sqrt[3]{\frac{24}{k^2}}\) inside the radical and simplify, assuming \(k>0\). b) A student claims, “\(-3\sqrt2=\sqrt{(-3)^2\cdot2}=\sqrt{18}\).” Explain the error and give the correct transformed expression.

Hints

- Cube the entire outside factor in part a. - Check whether a transformation preserves the sign of the original expression. - A principal square root cannot be negative.

Solution

1. \(\frac{k}{2}\sqrt[3]{\frac{24}{k^2}}=\sqrt[3]{\left(\frac{k}{2}\right)^3\frac{24}{k^2}}=\sqrt[3]{3k}\). 2. The original expression is negative, but \(\sqrt{18}\) is nonnegative. A negative sign cannot be moved inside a square root by squaring the coefficient. The correct transformation is \(-3\sqrt2=-\sqrt{18}\).

Answer

a) \(\sqrt[3]{3k}\) b) The claim is false. The correct expression is \(-\sqrt{18}\).
52476611
Let \(T=\frac{2a^2}{3b}\sqrt[4]{\frac{27b^5}{8a^6}}\), where \(a>0\) and \(b>0\). Write \(T\) in the form \(\frac1k\sqrt[4]{P}\), where \(k\) is a natural number and \(P\) is a polynomial expression with no denominator.

Hints

- Move the entire outside fraction inside the fourth root. - Simplify all numerical and variable powers in the radicand. - Multiply the radicand fraction so its denominator becomes a perfect fourth power.

Solution

1. Move the outside factor inside the fourth root: \(T=\sqrt[4]{\left(\frac{2a^2}{3b}\right)^4\frac{27b^5}{8a^6}}\). 2. Simplify the radicand: \(\left(\frac{2a^2}{3b}\right)^4\frac{27b^5}{8a^6}=\frac{16a^8}{81b^4}\cdot\frac{27b^5}{8a^6}=\frac{2a^2b}{3}\). 3. Make the denominator a fourth power: \(\sqrt[4]{\frac{2a^2b}{3}}=\sqrt[4]{\frac{54a^2b}{81}}=\frac13\sqrt[4]{54a^2b}\).

Answer

\(\frac13\sqrt[4]{54a^2b}\)
52477411
Simplify for \(a>b>0\) and a natural number \(n\geq2\): \(\frac{a^2-b^2}{a+b}\sqrt[n]{\frac{(a+b)^n}{(a-b)^{n-1}}}\)

Hints

- Simplify the fraction outside the radical first. - Use the difference-of-squares identity. - Rewrite the radical denominator as a rational exponent and subtract exponents.

Solution

1. Use the difference of squares: \(\frac{a^2-b^2}{a+b}=a-b\). 2. Because \(a>b>0\), \(\sqrt[n]{\frac{(a+b)^n}{(a-b)^{n-1}}}=\frac{a+b}{(a-b)^{\frac{n-1}{n}}}\). 3. Multiply and combine powers: \((a-b)\frac{a+b}{(a-b)^{\frac{n-1}{n}}}=(a+b)(a-b)^{\frac1n}=(a+b)\sqrt[n]{a-b}\).

Answer

\((a+b)\sqrt[n]{a-b}\)
52480411
Determine whether the radical terms in each group are like terms after simplification. Assume all variables are positive and \(n\geq2\) is a natural number. 1) \(\sqrt[n]{a^{n+2}b}\), \(a\sqrt[n]{a^2b}\), and \(\frac1a\sqrt[n]{a^{2n+2}b}\) 2) \(\sqrt[4]{\frac{x^5}{y^3}}\), \(\frac{x}{y}\sqrt[4]{xy}\), and \(\frac1x\sqrt[4]{x^9y}\)

Hints

- Extract powers whose exponents are multiples of the radical index. - For a fraction inside a radical, make the denominator a perfect power. - Like radical terms have the same index and the same simplified radicand.

Solution

1. The first expression is \(a\sqrt[n]{a^2b}\). The second already has that form. The third is \(\frac1a\cdot a^2\sqrt[n]{a^2b}=a\sqrt[n]{a^2b}\). All three are identical. 2. \(\sqrt[4]{\frac{x^5}{y^3}}=\frac{x}{y}\sqrt[4]{xy}\). The second expression already has that radical part. The third is \(\frac1x\cdot x^2\sqrt[4]{xy}=x\sqrt[4]{xy}\). All three have the same radical part \(\sqrt[4]{xy}\), so they are like radical terms.

Answer

1) All three terms are identical and therefore like terms. 2) All three terms are like radical terms with radical part \(\sqrt[4]{xy}\).
52490411
Factor each expression completely. Assume \(x,a\ge0\). 1) \(x-10\sqrt{x}+25\) 2) \(3a-5\sqrt{a}-2\)

Hints

- Substitute a new variable for the square root. - Treat the resulting expression as a quadratic polynomial. - Look for a perfect-square trinomial in part 1. - Substitute the original radical expression back after factoring.

Solution

1. Let \(u=\sqrt{x}\). Then the expression is \(u^2-10u+25=(u-5)^2\). Substituting back gives \((\sqrt{x}-5)^2\). 2. Let \(u=\sqrt{a}\). Then \(3a-5\sqrt{a}-2=3u^2-5u-2\). Factor the quadratic: \(3u^2-5u-2=(u-2)(3u+1)\). Substituting back gives \((\sqrt{a}-2)(3\sqrt{a}+1)\).

Answer

1) \((\sqrt{x}-5)^2\) 2) \((\sqrt{a}-2)(3\sqrt{a}+1)\)
52496411
Nested radicals of the form \(\sqrt{a\pm\sqrt{b}}\) can sometimes be rewritten as sums or differences of simpler radicals. 1. Verify by squaring that \(\sqrt{10-\sqrt{84}}=\sqrt{7}-\sqrt{3}\). 2. Find rational numbers \(x\) and \(y\) such that \(\sqrt{4.5+\sqrt{8}}=\sqrt{x}+\sqrt{y}\). 3. To write \(\sqrt{a+2\sqrt{b}}\) as \(\sqrt{x}+\sqrt{y}\), what conditions must \(x\) and \(y\) satisfy?

Hints

- Square the simpler radical expression. - Compare the rational part and the radical part after squaring. - Use the sum and product of \(x\) and \(y\). - Compare coefficients carefully when radical terms have different outside factors.

Solution

1. \((\sqrt{7}-\sqrt{3})^2=7-2\sqrt{21}+3=10-\sqrt{84}\), and \(\sqrt{7}-\sqrt{3}>0\). Therefore, the equation is true. 2. Squaring the proposed form gives \(x+y+2\sqrt{xy}=4.5+2\sqrt{2}\). Thus, \(x+y=4.5\) and \(xy=2\). The values are \(x=4\) and \(y=0.5\), in either order. 3. For nonnegative \(x\) and \(y\), \((\sqrt{x}+\sqrt{y})^2=x+y+2\sqrt{xy}\). Therefore, the required conditions are \(x+y=a\) and \(xy=b\).

Answer

1. The equation is true. 2. \(x=4\) and \(y=0.5\), in either order 3. \(x,y\ge0\), \(x+y=a\), and \(xy=b\)
52504411
Let \(x=\frac{\sqrt{a}+1}{\sqrt{a}-1}\) and \(y=\frac{\sqrt{a}-1}{\sqrt{a}+1}\), where \(a>0\) and \(a\ne1\). Show that \(S=\frac{x-y}{x+y}\) simplifies to \(\frac{2\sqrt{a}}{a+1}\).

Hints

- Compute \(x-y\) and \(x+y\) separately using a common denominator. - Expand the squared binomials in the new numerators. - Use \(\sqrt{a}\cdot\sqrt{a}=a\) when simplifying products. - Keep the factor \(a-1\) visible so it can be canceled in the final complex fraction.

Solution

1. Using the common denominator \((\sqrt{a}-1)(\sqrt{a}+1)=a-1\), \(x-y=\frac{(\sqrt{a}+1)^2-(\sqrt{a}-1)^2}{a-1}=\frac{4\sqrt{a}}{a-1}\). 2. Similarly, \(x+y=\frac{(\sqrt{a}+1)^2+(\sqrt{a}-1)^2}{a-1}=\frac{2(a+1)}{a-1}\). 3. Therefore, \(S=\frac{4\sqrt{a}/(a-1)}{2(a+1)/(a-1)}=\frac{2\sqrt{a}}{a+1}\).

Answer

\(S=\frac{2\sqrt{a}}{a+1}\)
52504811
Simplify \(E=\frac{x+\sqrt{x^2-1}}{x-\sqrt{x^2-1}}\) when \(x=\frac{1}{2}\left(\sqrt{a}+\frac{1}{\sqrt{a}}\right)\) and \(a>1\).

Hints

- Substitute the expression for \(x\) into \(x^2-1\) and rewrite the result as a perfect square. - Use \(a>1\) to determine the sign when taking the square root. - Simplify the numerator and denominator of \(E\) separately.

Solution

1. Substitute for \(x\): \(x^2-1=\frac{1}{4}\left(a+2+\frac{1}{a}\right)-1=\frac{1}{4}\left(a-2+\frac{1}{a}\right)=\left[\frac{1}{2}\left(\sqrt{a}-\frac{1}{\sqrt{a}}\right)\right]^2\). 2. Since \(a>1\), \(\sqrt{a}-\frac{1}{\sqrt{a}}>0\). Thus, \(\sqrt{x^2-1}=\frac{1}{2}\left(\sqrt{a}-\frac{1}{\sqrt{a}}\right)\). 3. Then \(x+\sqrt{x^2-1}=\sqrt{a}\), while \(x-\sqrt{x^2-1}=\frac{1}{\sqrt{a}}\). 4. Therefore, \(E=\frac{\sqrt{a}}{1/\sqrt{a}}=a\).

Answer

\(E=a\)
52505011
Evaluate \(2x^3-2x^2+3x+2\) for \(x=\frac{1+\sqrt{3}}{2}\).

Hints

- Isolate the radical in the equation defining \(x\), then square. - Use the resulting quadratic relation to reduce higher powers of \(x\). - Rewrite the cubic expression to include a factor known to equal zero. - Consider polynomial division or strategic factoring if a cubic remains.

Solution

1. From \(2x-1=\sqrt{3}\), squaring gives \(4x^2-4x+1=3\), so \(2x^2-2x-1=0\). 2. Rewrite the expression as \(x(2x^2-2x-1)+4x+2\). 3. The factor in parentheses equals \(0\), so the value is \(4x+2\). 4. Substituting gives \(4\left(\frac{1+\sqrt{3}}{2}\right)+2=4+2\sqrt{3}\).

Answer

\(4+2\sqrt{3}\)
52506211
Let \(T=\frac{\sqrt{x+2}+\sqrt{x-2}}{\sqrt{x+2}-\sqrt{x-2}}\). Find \(T\) in terms of \(a\) and \(b\) when \(x=\frac{a}{b}+\frac{b}{a}\) and \(a>b>0\).

Hints

- Rewrite \(x+2\) and \(x-2\) over the common denominator \(ab\). - Recognize perfect-square trinomials in the numerators. - Use \(a>b>0\) when taking square roots. - Simplify the numerator and denominator of the complex fraction separately.

Solution

1. Substitute for \(x\): \(x+2=\frac{a^2+b^2+2ab}{ab}=\frac{(a+b)^2}{ab}\), and \(x-2=\frac{a^2+b^2-2ab}{ab}=\frac{(a-b)^2}{ab}\). 2. Since \(a>b>0\), \(\sqrt{x+2}=\frac{a+b}{\sqrt{ab}}\) and \(\sqrt{x-2}=\frac{a-b}{\sqrt{ab}}\). 3. The numerator of \(T\) is \(\frac{2a}{\sqrt{ab}}\), and the denominator is \(\frac{2b}{\sqrt{ab}}\). 4. Therefore, \(T=\frac{2a/\sqrt{ab}}{2b/\sqrt{ab}}=\frac{a}{b}\).

Answer

\(\frac{a}{b}\)
52809211
For \(0<x<y\), simplify by moving the factor outside the radical under the radical sign: \(\frac{x-y}{x}\sqrt{\frac{x^3}{y^2-x^2}}\)

Hints

- Use \(0<x<y\) to determine the sign of the outside factor. - Keep a negative sign outside when moving the positive magnitude under the radical. - Factor the difference of squares in the denominator. - Cancel common factors inside the radicand.

Solution

1. Since \(0<x<y\), \(\frac{x-y}{x}<0\). Rewrite it as \(-\frac{y-x}{x}\), where \(\frac{y-x}{x}>0\). 2. Move the positive factor under the radical by squaring it: \(-\sqrt{\frac{(y-x)^2}{x^2}\cdot\frac{x^3}{y^2-x^2}}\). 3. Factor \(y^2-x^2=(y-x)(y+x)\), then cancel common factors. The radicand becomes \(\frac{x(y-x)}{x+y}\). 4. Therefore, the simplified expression is \(-\sqrt{\frac{x(y-x)}{x+y}}\).

Answer

\(-\sqrt{\frac{x(y-x)}{x+y}}\)

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