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Complete the square

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5101519
Solve \(x^2 + 2x - 3 = 0\) by completing the square.

Hints

- Move the constant term to the other side. - Add the value that turns the left side into a perfect-square trinomial. - Use both square roots when solving the resulting equation.

Solution

1. Move the constant term: \(x^2 + 2x = 3\). 2. Add \(1\) to both sides: \(x^2 + 2x + 1 = 4\). 3. Rewrite the left side: \((x + 1)^2 = 4\). 4. Take both square roots: \(x + 1 = \pm 2\). 5. Therefore, \(x = 1\) or \(x = -3\).

Answer

\(x = 1\) or \(x = -3\)
5101529
Solve \(x^2 - 4x + 1 = 0\) by completing the square.

Hints

- Move the constant term to the other side. - Complete the square on the left side. - Keep the solutions in exact radical form and use both square roots.

Solution

1. Move the constant term: \(x^2 - 4x = -1\). 2. Add \(4\) to both sides: \(x^2 - 4x + 4 = 3\). 3. Rewrite the left side: \((x - 2)^2 = 3\). 4. Take both square roots: \(x - 2 = \pm\sqrt{3}\). 5. Therefore, \(x = 2 + \sqrt{3}\) or \(x = 2 - \sqrt{3}\).

Answer

\(x = 2 + \sqrt{3}\) or \(x = 2 - \sqrt{3}\)
5101539
Solve \(x^2 + 10x + 17 = 0\) by completing the square.

Hints

- Move the constant term to the other side. - Use half the coefficient of \(x\) to determine what to add to both sides. - Simplify the radical after taking both square roots.

Solution

1. Move the constant term: \(x^2 + 10x = -17\). 2. Add \(25\) to both sides: \(x^2 + 10x + 25 = 8\). 3. Rewrite the left side: \((x + 5)^2 = 8\). 4. Take both square roots and simplify: \(x + 5 = \pm\sqrt{8} = \pm 2\sqrt{2}\). 5. Therefore, \(x = -5 + 2\sqrt{2}\) or \(x = -5 - 2\sqrt{2}\).

Answer

\(x = -5 + 2\sqrt{2}\) or \(x = -5 - 2\sqrt{2}\)
5145109
Rewrite each quadratic in vertex form by recognizing a perfect-square trinomial or completing the square. Then state the vertex. a) \(f(x) = x^2 - 12x + 36\) b) \(g(x) = x^2 + 5x + 6.25\) c) \(h(x) = x^2 - 2x + 5\)

Hints

- Do the first two expressions match a perfect-square trinomial pattern? - For c), what number completes the square for \(x^2 - 2x\)? - How can you rewrite the constant term so that part of it completes the square?

Solution

1. For a), \(x^2 - 12x + 36 = x^2 - 2 \cdot 6x + 6^2 = (x - 6)^2\). Thus, \(f(x) = (x - 6)^2\), and the vertex is \((6, 0)\). 2. For b), \(6.25 = 2.5^2\), so \(x^2 + 5x + 6.25 = x^2 + 2 \cdot 2.5x + 2.5^2 = (x + 2.5)^2\). Thus, \(g(x) = (x + 2.5)^2\), and the vertex is \((-2.5, 0)\). 3. For c), complete the square: \(x^2 - 2x + 5 = x^2 - 2x + 1 + 4 = (x - 1)^2 + 4\). Thus, \(h(x) = (x - 1)^2 + 4\), and the vertex is \((1, 4)\).

Answer

a) \(f(x) = (x - 6)^2\); vertex \((6, 0)\) b) \(g(x) = (x + 2.5)^2\); vertex \((-2.5, 0)\) c) \(h(x) = (x - 1)^2 + 4\); vertex \((1, 4)\)
5145459
Fill in each missing constant so that the vertex of the translated parabola lies on the x-axis. Then state the vertex. a) \(f(x)=x^2+12x+\ldots\) b) \(g(x)=x^2-18x+\ldots\) c) \(h(x)=x^2+7x+\ldots\)

Hints

- Relate the linear term to a squared binomial. - What must the vertex's y-coordinate be when the vertex lies on the x-axis? - For \(x^2+px+q\), how is \(q\) related to half of \(p\)?

Solution

1. A monic quadratic with its vertex on the x-axis is a perfect square. For \(x^2+px+q\), the required constant is \(q=\left(\frac{p}{2}\right)^2\). 2. For \(f\), \(\left(\frac{12}{2}\right)^2=36\). Thus, \(f(x)=x^2+12x+36=(x+6)^2\), with vertex \((-6, 0)\). 3. For \(g\), \(\left(\frac{-18}{2}\right)^2=81\). Thus, \(g(x)=x^2-18x+81=(x-9)^2\), with vertex \((9, 0)\). 4. For \(h\), \(\left(\frac{7}{2}\right)^2=12.25\). Thus, \(h(x)=x^2+7x+12.25=(x+3.5)^2\), with vertex \((-3.5, 0)\).

Answer

a) \(f(x)=x^2+12x+36\); vertex \((-6, 0)\) b) \(g(x)=x^2-18x+81\); vertex \((9, 0)\) c) \(h(x)=x^2+7x+12.25\); vertex \((-3.5, 0)\)
5145639
Let \(f(x) = x^2 + 10x + 7\). Complete the square to rewrite the function in vertex form. Then state the vertex and determine whether it is a maximum or a minimum.

Hints

- What number completes the square for \(x^2 + 10x\)? - How does the sign inside the squared binomial determine the vertex's \(x\)-coordinate? - What does the sign of the leading coefficient tell you about the opening of the parabola?

Solution

1. Half of \(10\) is \(5\), and \(5^2 = 25\). 2. Add and subtract \(25\): \(f(x) = x^2 + 10x + 25 - 25 + 7\). 3. Rewrite the perfect-square trinomial: \(f(x) = (x + 5)^2 - 18\). 4. The vertex is \((-5, -18)\). Since the coefficient of the squared term is positive, the parabola opens upward, so the vertex is a minimum.

Answer

The vertex form is \(f(x) = (x + 5)^2 - 18\). The vertex is \((-5, -18)\), and it is a minimum.
5146149
Rewrite \(f(x) = x^2 + 4x + 7\) in vertex form and state the vertex.

Hints

- What number completes the square for \(x^2 + 4x\)? - Remember to subtract the same value you add. - How do you read the vertex from \(a(x - h)^2 + k\)?

Solution

1. Complete the square: \(x^2 + 4x + 7 = x^2 + 4x + 4 - 4 + 7\). 2. Rewrite and simplify: \(f(x) = (x + 2)^2 + 3\). 3. Therefore, the vertex is \((-2, 3)\).

Answer

\(f(x) = (x + 2)^2 + 3\); vertex \((-2, 3)\)
5153169
Solve \(x^2 + 2x - 4 = 0\) by completing the square. Give the solutions in exact radical form.

Hints

- Move the constant term to the other side. - Add the value needed to form a perfect-square trinomial. - Use both square roots and keep the answer in exact form.

Solution

1. Move the constant term: \(x^2 + 2x = 4\). 2. Add \(1\) to both sides: \(x^2 + 2x + 1 = 5\). 3. Rewrite the left side: \((x + 1)^2 = 5\). 4. Take both square roots: \(x + 1 = \pm\sqrt{5}\). 5. Therefore, \(x = -1 + \sqrt{5}\) or \(x = -1 - \sqrt{5}\).

Answer

\(x = -1 + \sqrt{5}\) or \(x = -1 - \sqrt{5}\)
5153189
Solve \(x^2 + 4x - 4 = 0\) by completing the square. Give the solutions in exact form and simplify each radical.

Hints

- Move the constant term before completing the square. - Add the square of half the coefficient of \(x\). - After taking square roots, simplify the radical.

Solution

1. Move the constant term: \(x^2 + 4x = 4\). 2. Add \(4\) to both sides: \(x^2 + 4x + 4 = 8\). 3. Rewrite the left side: \((x + 2)^2 = 8\). 4. Take both square roots: \(x + 2 = \pm\sqrt{8} = \pm 2\sqrt{2}\). 5. Therefore, \(x = -2 + 2\sqrt{2}\) or \(x = -2 - 2\sqrt{2}\).

Answer

\(x = -2 + 2\sqrt{2}\) or \(x = -2 - 2\sqrt{2}\)
5251159
Solve each quadratic equation by completing the square. 1) \(x^2 + 10x - 24 = 0\) 2) \(x^2 - 16x = -15\)

Hints

- Write each equation in the form \(x^2 + bx = c\). - Add the square of half the coefficient of \(x\) to both sides. - Use both square roots after forming a perfect square.

Solution

1. For equation 1, write \(x^2 + 10x = 24\). Add \(25\) to both sides: \((x + 5)^2 = 49\). 2. Take both square roots: \(x + 5 = \pm 7\). Thus, \(x = 2\) or \(x = -12\). 3. For equation 2, add \(64\) to both sides: \((x - 8)^2 = 49\). 4. Take both square roots: \(x - 8 = \pm 7\). Thus, \(x = 15\) or \(x = 1\).

Answer

1) \(x \in \{-12, 2\}\) 2) \(x \in \{1, 15\}\)
5251299
Solve each quadratic equation by completing the square. a) \(x^2 + 4x - 21 = 0\) b) \(x^2 - 6x + 5 = 0\)

Hints

- Move the constant term to the other side. - Add the square of half the coefficient of \(x\) to both sides. - Use both square roots.

Solution

1. For part a, write \(x^2 + 4x = 21\). Add \(4\) to both sides: \((x + 2)^2 = 25\). 2. Take both square roots: \(x + 2 = \pm 5\). Thus, \(x = 3\) or \(x = -7\). 3. For part b, write \(x^2 - 6x = -5\). Add \(9\) to both sides: \((x - 3)^2 = 4\). 4. Take both square roots: \(x - 3 = \pm 2\). Thus, \(x = 5\) or \(x = 1\).

Answer

a) \(x \in \{-7, 3\}\) b) \(x \in \{1, 5\}\)
5101509
Solve \(4x^2 - 16x - 9 = 0\) by completing the square.

Hints

- First isolate the terms containing \(x\) and make the coefficient of \(x^2\) equal to \(1\). - Add the value needed to create a perfect-square trinomial. - Remember to use both the positive and negative square roots.

Solution

1. Move the constant term and divide by \(4\): \(4x^2 - 16x = 9\), so \(x^2 - 4x = \frac{9}{4}\). 2. Add \(4\) to both sides: \(x^2 - 4x + 4 = \frac{9}{4} + 4\). 3. Rewrite and simplify: \((x - 2)^2 = \frac{25}{4}\). 4. Take both square roots: \(x - 2 = \pm\frac{5}{2}\). 5. Therefore, \(x = \frac{9}{2}\) or \(x = -\frac{1}{2}\).

Answer

\(x = \frac{9}{2}\) or \(x = -\frac{1}{2}\)
5101549
Solve \(4x^2 - 24x + 29 = 0\) by completing the square.

Hints

- Make the coefficient of \(x^2\) equal to \(1\) before completing the square. - Add the value needed to form a perfect-square trinomial. - Keep the final solutions in exact radical form.

Solution

1. Move the constant term and divide by \(4\): \(4x^2 - 24x = -29\), so \(x^2 - 6x = -\frac{29}{4}\). 2. Add \(9\) to both sides: \(x^2 - 6x + 9 = -\frac{29}{4} + 9\). 3. Rewrite and simplify: \((x - 3)^2 = \frac{7}{4}\). 4. Take both square roots: \(x - 3 = \pm\frac{\sqrt{7}}{2}\). 5. Therefore, \(x = 3 + \frac{\sqrt{7}}{2}\) or \(x = 3 - \frac{\sqrt{7}}{2}\).

Answer

\(x = 3 + \frac{\sqrt{7}}{2}\) or \(x = 3 - \frac{\sqrt{7}}{2}\)
5142759
Use completing the square to rewrite \(f(x)=2x^2-12x+10\) in vertex form. State the vertex and describe the transformations from the parent function \(y=x^2\).

Hints

- Before completing the square, what should you do with the coefficient of \(x^2\)? - How do you find the number needed to complete the square? - In vertex form, how does the sign inside the parentheses determine the horizontal shift? - How does a coefficient outside the squared expression affect the parabola?

Solution

1. Factor \(2\) from the quadratic and linear terms: \(f(x)=2(x^2-6x)+10\). 2. Complete the square inside the parentheses using \(\left(\frac{-6}{2}\right)^2=9\): \(f(x)=2(x^2-6x+9-9)+10\). 3. Rewrite the perfect-square trinomial: \(f(x)=2((x-3)^2-9)+10\). 4. Distribute and simplify: \(f(x)=2(x-3)^2-18+10=2(x-3)^2-8\). 5. The vertex is \((3, -8)\). 6. Relative to \(y=x^2\), the graph is vertically stretched by a factor of \(2\), shifted \(3\) units right, and shifted \(8\) units down.

Answer

The vertex form is \(f(x)=2(x-3)^2-8\), and the vertex is \((3, -8)\). The graph is vertically stretched by a factor of \(2\), shifted \(3\) units right, and shifted \(8\) units down.
5142779
The functions \(g(x)=x^2-4x+7\) and \(h(x)=(x-2)^2+1\) are given. Use completing the square to find the vertex of \(g\). Then compare the two parabolas: Do they have the same axis of symmetry? Which graph is above the other, and what is the vertical distance between their vertices?

Hints

- How can completing the square reveal the vertex of \(g\)? - Compare the x-coordinates of the two vertices. - Compare the constant terms in the two vertex-form equations.

Solution

1. Complete the square for \(g\): \(g(x)=x^2-4x+4-4+7\). 2. Simplify to obtain vertex form: \(g(x)=(x-2)^2+3\). 3. Therefore, the vertex of \(g\) is \((2, 3)\). 4. From the equation for \(h\), its vertex is \((2, 1)\). 5. Both vertices have x-coordinate \(2\), so both parabolas have the axis of symmetry \(x=2\). 6. Because \(g(x)=h(x)+2\), the graph of \(g\) is \(2\) units above the graph of \(h\) for every x-value. The vertical distance between the vertices is \(3-1=2\) units.

Answer

The vertex of \(g\) is \((2, 3)\). Both parabolas have the axis of symmetry \(x=2\). The graph of \(g\) is \(2\) units above the graph of \(h\), and the vertical distance between their vertices is \(2\) units.
5145339
Find each real solution set without a calculator. Complete the square when needed. a) \(x^2 - 25 = 0\) b) \(x^2 - 2.4x + 0.8 = 0\) c) \(x^2 + 4x - 5 = 0\) d) \(x^2 + 8 = 0\)

Hints

- Isolate the squared expression first. - For a trinomial, add the value needed to create a perfect square. - When a positive square is isolated, remember both square roots. - Consider whether a real number can have a negative square.

Solution

1. For part a, \(x^2 = 25\), so \(x = \pm 5\). 2. For part b, write \(x^2 - 2.4x = -0.8\). Add \(1.44\) to both sides: \((x - 1.2)^2 = 0.64\). Then \(x - 1.2 = \pm 0.8\), so \(x = 2\) or \(x = 0.4\). 3. For part c, write \(x^2 + 4x = 5\). Add \(4\) to both sides: \((x + 2)^2 = 9\). Then \(x + 2 = \pm 3\), so \(x = 1\) or \(x = -5\). 4. For part d, \(x^2 = -8\). No real number has a negative square, so there is no real solution.

Answer

a) \(x \in \{-5, 5\}\) b) \(x \in \{0.4, 2\}\) c) \(x \in \{-5, 1\}\) d) \(\varnothing\)
5145359
Complete each task about real solutions of quadratic equations. a) Solve \(x^2 - \frac{1}{4} = 0\). b) Explain without calculating why \((x + 5)^2 = -4\) has no real solution. c) Solve \(x^2 - 2x - 3 = 0\) by completing the square.

Hints

- Recall that the square of a real number is never negative. - For part c, move the constant term and complete the square. - Use both square roots after isolating a square.

Solution

1. For part a, \(x^2 = \frac{1}{4}\), so \(x = \pm\frac{1}{2}\). 2. For part b, the square of any real expression is greater than or equal to zero. Therefore, \((x + 5)^2\) cannot equal \(-4\). 3. For part c, write \(x^2 - 2x = 3\). Add \(1\) to both sides: \((x - 1)^2 = 4\). Then \(x - 1 = \pm 2\), so \(x = 3\) or \(x = -1\).

Answer

a) \(x \in \left\{-\frac{1}{2}, \frac{1}{2}\right\}\) b) There is no real solution because the square of a real expression cannot be negative. c) \(x \in \{-1, 3\}\)
5145369
Maya claims, “If the vertex of a translation of \(y=x^2\) lies on the x-axis, then the function expression can be written as the square of a binomial.” Test the claim by analyzing each function. State whether its vertex lies on the x-axis and give the vertex coordinates. a) \(f(x)=x^2-14x+49\) b) \(g(x)=x^2+5x+6.25\) c) \(h(x)=x^2-2x-1\)

Hints

- Look for perfect-square trinomials. - What does vertex form look like when the vertex is on the x-axis? - What y-coordinate does every point on the x-axis have? - Complete the square when an expression is not already a perfect square.

Solution

1. For \(f(x)=x^2-14x+49\), factor the perfect-square trinomial: \(f(x)=(x-7)^2\). The vertex is \((7, 0)\), so it lies on the x-axis. 2. For \(g(x)=x^2+5x+6.25\), factor the perfect-square trinomial: \(g(x)=(x+2.5)^2\). The vertex is \((-2.5, 0)\), so it lies on the x-axis. 3. For \(h(x)=x^2-2x-1\), complete the square: \(h(x)=x^2-2x+1-2=(x-1)^2-2\). The vertex is \((1, -2)\), so it does not lie on the x-axis. 4. In general, a translation of \(y=x^2\) with vertex \((r, 0)\) has equation \(y=(x-r)^2\). Therefore, Maya's claim is correct.

Answer

Maya's claim is correct. a) Yes; the vertex is \((7, 0)\). b) Yes; the vertex is \((-2.5, 0)\). c) No; the vertex is \((1, -2)\).
5145379
The function is \(f(x)=x^2+12x+q\). Find the value of \(q\) that makes the vertex of the parabola lie on the x-axis. Then write the function in vertex form.

Hints

- What constant makes the trinomial a perfect square? - A parabola whose vertex is on the x-axis has what minimum value? - How is the coefficient \(12\) related to the number inside the binomial?

Solution

1. If the vertex lies on the x-axis, the quadratic must be a perfect square with minimum value \(0\). 2. Compare \(x^2+12x+q\) with \((x+r)^2=x^2+2rx+r^2\). 3. Since \(2r=12\), \(r=6\). Therefore, \(q=r^2=36\). 4. The vertex form is \(f(x)=(x+6)^2\), with vertex \((-6, 0)\).

Answer

\(q=36\), and the vertex form is \(f(x)=(x+6)^2\).
5145529
Consider \(x^2 + 4 = 2x\). a) Rewrite the equation so that \(x^2\) is alone on the left. b) Let \(f(x) = x^2\) and \(g(x) = 2x - 4\). Use algebra to determine whether the two functions can have the same output. c) How many real solutions does the original equation have, and what does this mean about the graphs of \(f\) and \(g\)?

Hints

- Isolate \(x^2\) first. - Move the two function expressions to one side and complete the square. - Equal outputs correspond to graph intersections.

Solution

1. Subtract \(4\) from both sides: \(x^2 = 2x - 4\). 2. Equal outputs would require \(x^2 - 2x + 4 = 0\). 3. Complete the square: \(x^2 - 2x + 4 = (x - 1)^2 + 3\). 4. Since \((x - 1)^2 + 3 > 0\) for every real \(x\), the functions never have the same output. 5. Therefore, the original equation has no real solutions, and the graphs have no intersection points.

Answer

a) \(x^2 = 2x - 4\) b) The functions never have the same output. c) No real solutions; the graphs have no intersection points.
5145559
The function \(g(x)=x^2+bx+64\) is given. a) Find the two values of \(b\) for which the graph touches the x-axis at exactly one point. b) Find the vertex when \(b\) is the positive value from part a.

Hints

- What form must the quadratic have when it has exactly one distinct real zero? - Which two real numbers have square \(64\)? - Compare the linear term with the expanded form of \((x-h)^2\).

Solution

1. A monic quadratic that touches the x-axis at exactly one point is a perfect square: \(g(x)=(x-h)^2=x^2-2hx+h^2\). 2. Compare constant terms: \(h^2=64\), so \(h=8\) or \(h=-8\). 3. Since \(b=-2h\), the corresponding values are \(b=-16\) and \(b=16\). 4. For the positive value \(b=16\), \(h=-8\), so \(g(x)=(x+8)^2\) and the vertex is \((-8, 0)\).

Answer

a) \(b=-16\) or \(b=16\) b) \((-8, 0)\)
5145569
A translated parent parabola is defined by \(h(x)=x^2-9x+c\). a) Find the value of \(c\) for which the vertex lies on the x-axis. b) Increase the value of \(c\) from part a by \(1.5\). Describe how the vertex changes.

Hints

- Complete the square by using half the coefficient of \(x\). - How does changing only the constant term affect the graph vertically? - Does the x-coordinate of the vertex change when the same constant is added to every output?

Solution

1. To place the vertex on the x-axis, write the function as a perfect square: \(h(x)=(x-r)^2=x^2-2rx+r^2\). 2. Compare linear coefficients: \(-2r=-9\), so \(r=4.5\). 3. Therefore, \(c=r^2=4.5^2=20.25\). 4. Increasing \(c\) by \(1.5\) adds \(1.5\) to every output: \(h_{\text{new}}(x)=(x-4.5)^2+1.5\). 5. The graph shifts \(1.5\) units upward, so the vertex moves from \((4.5, 0)\) to \((4.5, 1.5)\).

Answer

a) \(c=20.25\) b) The vertex shifts \(1.5\) units upward, from \((4.5, 0)\) to \((4.5, 1.5)\).
5145659
Rewrite \(g(x) = -0.5x^2 + 4x - 2\) in vertex form by completing the square. Also describe how the leading coefficient \(-0.5\) changes the graph compared with \(y = x^2\).

Hints

- What should you factor from the variable terms before completing the square? - Track the negative factor carefully when simplifying. - What do a negative leading coefficient and an absolute value between \(0\) and \(1\) do to a parabola?

Solution

1. Factor \(-0.5\) from the variable terms: \(g(x) = -0.5(x^2 - 8x) - 2\). 2. Complete the square inside the parentheses: \(g(x) = -0.5(x^2 - 8x + 16 - 16) - 2\). 3. Rewrite and simplify: \(g(x) = -0.5((x - 4)^2 - 16) - 2 = -0.5(x - 4)^2 + 8 - 2 = -0.5(x - 4)^2 + 6\). 4. The negative sign reflects the parabola across the \(x\)-axis, so it opens downward. Because \(|-0.5| < 1\), the graph is vertically compressed and therefore wider than \(y = x^2\).

Answer

The vertex form is \(g(x) = -0.5(x - 4)^2 + 6\). The graph opens downward and is wider than \(y = x^2\).
5146019
Solve \(x^2 + 8x + 12 = 0\) in two ways: 1. Complete the square. 2. Use the quadratic formula. Compare the intermediate forms. What advantage does completing the square provide when you interpret the related function as a parabola?

Hints

- To complete the square, add and subtract the square of half the coefficient of \(x\). - For the quadratic formula, identify \(a\), \(b\), and \(c\). - In vertex form, the vertex coordinates can be read from the expression.

Solution

1. Complete the square: \(x^2 + 8x + 12 = (x + 4)^2 - 4\). The equation becomes \((x + 4)^2 = 4\), so \(x + 4 = \pm 2\). Thus, \(x = -2\) or \(x = -6\). 2. Use the quadratic formula with \(a = 1\), \(b = 8\), and \(c = 12\): \(x = \frac{-8 \pm \sqrt{8^2 - 4 \cdot 1 \cdot 12}}{2 \cdot 1} = \frac{-8 \pm 4}{2}\). Thus, \(x = -2\) or \(x = -6\). 3. Both methods give the same solutions. Completing the square also gives the vertex form \(f(x) = (x + 4)^2 - 4\), so the vertex \((-4, -4)\) can be identified directly.

Answer

1. \(x \in \{-6, -2\}\) 2. \(x \in \{-6, -2\}\) Comparison: Completing the square produces vertex form, which shows the vertex \((-4, -4)\) directly.
5146159
Use completing the square to rewrite \(g(x) = -2x^2 + 12x - 10\) in vertex form.

Hints

- What factor should you take out of the variable terms first? - Track the outside factor when you add and subtract the value that completes the square. - Which perfect-square trinomial appears inside the parentheses?

Solution

1. Factor \(-2\) from the variable terms: \(g(x) = -2(x^2 - 6x) - 10\). 2. Complete the square inside the parentheses: \(g(x) = -2(x^2 - 6x + 9 - 9) - 10\). 3. Rewrite and simplify: \(g(x) = -2((x - 3)^2 - 9) - 10 = -2(x - 3)^2 + 18 - 10 = -2(x - 3)^2 + 8\).

Answer

\(g(x) = -2(x - 3)^2 + 8\)
5152409
Consider the equations (1) \(x^2 - 10x + 25 = 0\) (2) \(x^2 - 10x + 24 = 0\) a) Solve equation (1) by recognizing a perfect-square trinomial. b) Explain why equation (2) is not a perfect-square trinomial. How would the constant term need to change to make it one?

Hints

- Square half the coefficient of \(x\). - Compare that square with the constant term in each equation. - A perfect-square trinomial has the form \((x - h)^2\).

Solution

1. In equation (1), half the coefficient of \(x\) is \(-5\), and \((-5)^2 = 25\). Therefore, \(x^2 - 10x + 25 = (x - 5)^2\). 2. Solve \((x - 5)^2 = 0\): \(x = 5\). 3. For equation (2), a perfect-square trinomial with middle term \(-10x\) must have constant term \(\left(\frac{-10}{2}\right)^2 = 25\). 4. Since the constant term is \(24\), it must be increased by \(1\) to make the expression a perfect-square trinomial.

Answer

a) \(x = 5\) b) The constant term must be \(25\), so \(24\) must be increased by \(1\).
5152789
Let \(f(x) = x^2 - 4x - 5\). a) Complete the square to rewrite the function in vertex form and state the vertex. b) Find the zeros of the function.

Hints

- What number completes the square for \(x^2 - 4x\)? - Remember to add and subtract the same value. - Can you find the zeros directly from vertex form? - How can substitution check each zero?

Solution

1. Complete the square: \(f(x) = x^2 - 4x + 4 - 4 - 5 = (x - 2)^2 - 9\). The vertex is \((2, -9)\). 2. Set the vertex form equal to zero: \((x - 2)^2 - 9 = 0\), so \((x - 2)^2 = 9\). Then \(x - 2 = \pm 3\), giving \(x = -1\) or \(x = 5\).

Answer

a) \(f(x) = (x - 2)^2 - 9\); vertex \((2, -9)\) b) \(x = -1\) and \(x = 5\)
5152999
Let \(g(x) = -2x^2 + 8x - 5\). Complete the square to rewrite the function in vertex form. Then state the vertex and identify the quadrant in which it lies.

Hints

- What factor should you take out of the variable terms before completing the square? - Remember to distribute the outside factor to both terms when simplifying. - What signs do the coordinates of a point in Quadrant I have?

Solution

1. Factor \(-2\) from the variable terms: \(g(x) = -2(x^2 - 4x) - 5\). 2. Complete the square: \(g(x) = -2(x^2 - 4x + 4 - 4) - 5\). 3. Rewrite and simplify: \(g(x) = -2((x - 2)^2 - 4) - 5 = -2(x - 2)^2 + 8 - 5 = -2(x - 2)^2 + 3\). 4. The vertex is \((2, 3)\). Since both coordinates are positive, the vertex lies in Quadrant I.

Answer

The vertex form is \(g(x) = -2(x - 2)^2 + 3\). The vertex is \((2, 3)\), which lies in Quadrant I.
5251169
Find each solution set by completing the square. 1) \(x^2 - 7x + 10 = 0\) 2) \(x^2 + 9x = 10\)

Hints

- Half of an odd coefficient will be a fraction. - Square half the coefficient of \(x\) and add that value to both sides. - Keep the work in exact fractional form.

Solution

1. For equation 1, write \(x^2 - 7x = -10\). Add \(\frac{49}{4}\) to both sides: \(\left(x - \frac{7}{2}\right)^2 = \frac{9}{4}\). 2. Take both square roots: \(x - \frac{7}{2} = \pm\frac{3}{2}\). Thus, \(x = 5\) or \(x = 2\). 3. For equation 2, add \(\frac{81}{4}\) to both sides: \(\left(x + \frac{9}{2}\right)^2 = \frac{121}{4}\). 4. Take both square roots: \(x + \frac{9}{2} = \pm\frac{11}{2}\). Thus, \(x = 1\) or \(x = -10\).

Answer

1) \(x \in \{2, 5\}\) 2) \(x \in \{-10, 1\}\)
5251179
Solve each quadratic equation by completing the square. 1) \(x^2 - 16x + 63 = 0\) 2) \(x^2 + 7x = 18\)

Hints

- Isolate the terms containing \(x\). - Add the square of half the coefficient of \(x\) to both sides. - Use both square roots and simplify exactly.

Solution

1. For equation 1, write \(x^2 - 16x = -63\). Add \(64\) to both sides: \((x - 8)^2 = 1\). 2. Take both square roots: \(x - 8 = \pm 1\). Thus, \(x = 9\) or \(x = 7\). 3. For equation 2, add \(\frac{49}{4}\) to both sides: \(\left(x + \frac{7}{2}\right)^2 = \frac{121}{4}\). 4. Take both square roots: \(x + \frac{7}{2} = \pm\frac{11}{2}\). Thus, \(x = 2\) or \(x = -9\).

Answer

1) \(x \in \{7, 9\}\) 2) \(x \in \{-9, 2\}\)
5251189
Find each solution set by completing the square. 1) \(3x^2 - 12x = 36\) 2) \(x^2 - 3x = \frac{7}{4}\)

Hints

- Make the coefficient of \(x^2\) equal to \(1\) before completing the square. - Add the square of half the coefficient of \(x\) to both sides. - Use exact fractions in the solution set.

Solution

1. For equation 1, divide by \(3\): \(x^2 - 4x = 12\). Add \(4\) to both sides: \((x - 2)^2 = 16\). 2. Take both square roots: \(x - 2 = \pm 4\). Thus, \(x = 6\) or \(x = -2\). 3. For equation 2, add \(\frac{9}{4}\) to both sides: \(\left(x - \frac{3}{2}\right)^2 = 4\). 4. Take both square roots: \(x - \frac{3}{2} = \pm 2\). Thus, \(x = \frac{7}{2}\) or \(x = -\frac{1}{2}\).

Answer

1) \(x \in \{-2, 6\}\) 2) \(x \in \left\{-\frac{1}{2}, \frac{7}{2}\right\}\)
5251309
Find each solution set by completing the square. a) \(x^2 - x - \frac{3}{4} = 0\) b) \(3x^2 + 12x - 15 = 0\)

Hints

- Use exact fractions rather than decimals. - Make the coefficient of \(x^2\) equal to \(1\) before completing the square. - Add the same completing-square value to both sides.

Solution

1. For part a, write \(x^2 - x = \frac{3}{4}\). Add \(\frac{1}{4}\) to both sides: \(\left(x - \frac{1}{2}\right)^2 = 1\). 2. Take both square roots: \(x - \frac{1}{2} = \pm 1\). Thus, \(x = \frac{3}{2}\) or \(x = -\frac{1}{2}\). 3. For part b, divide by \(3\): \(x^2 + 4x - 5 = 0\). Write \(x^2 + 4x = 5\). 4. Add \(4\) to both sides: \((x + 2)^2 = 9\). 5. Take both square roots: \(x + 2 = \pm 3\). Thus, \(x = 1\) or \(x = -5\).

Answer

a) \(x \in \left\{-\frac{1}{2}, \frac{3}{2}\right\}\) b) \(x \in \{-5, 1\}\)
5254659
The quadratic function is \(f(x) = 0.5x^2 - 3x + 5.5\). a) Use the discriminant to show that the graph has no x-intercepts. b) Write the function in vertex form. Use that form to explain why every function value is at least \(1\). c) State the range of the function.

Hints

- Calculate the discriminant from standard form. - Factor out \(0.5\) from the quadratic and linear terms before completing the square. - Read the minimum value from vertex form.

Solution

1. The discriminant is \(D = (-3)^2 - 4 \cdot 0.5 \cdot 5.5 = 9 - 11 = -2\). Since \(D < 0\), the graph has no x-intercepts. 2. Complete the square: \(f(x) = 0.5(x^2 - 6x) + 5.5 = 0.5\left((x - 3)^2 - 9\right) + 5.5\). 3. Thus, \(f(x) = 0.5(x - 3)^2 + 1\). 4. Since \((x - 3)^2 \ge 0\), it follows that \(0.5(x - 3)^2 + 1 \ge 1\). 5. The minimum value is \(1\), so the range is \([1, \infty)\).

Answer

a) \(D = -2\), so there are no x-intercepts. b) \(f(x) = 0.5(x - 3)^2 + 1\), so \(f(x) \ge 1\). c) \([1, \infty)\)
5334399
Given \(f(x) = 1.5x^2 - 6x + 4.5\): a) Rewrite \(f\) in vertex form by completing the square. b) Use the vertex form to find the zeros. c) Write \(f\) in factored form. d) Check your results on the graph.
Figure for problem 533439

Hints

- Factor out the leading coefficient before completing the square. - Set the vertex form equal to zero and isolate the squared expression. - Use the zeros to write the factors.

Solution

1. Factor \(1.5\) from the quadratic and linear terms: \(f(x) = 1.5(x^2 - 4x) + 4.5\). 2. Complete the square: \(f(x) = 1.5((x - 2)^2 - 4) + 4.5 = 1.5(x - 2)^2 - 1.5\). 3. Set the vertex form equal to zero: \(1.5(x - 2)^2 - 1.5 = 0\). Then \((x - 2)^2 = 1\), so \(x - 2 = \pm 1\). The zeros are \(x = 1\) and \(x = 3\). 4. The factored form is \(f(x) = 1.5(x - 1)(x - 3)\). 5. The graph confirms vertex \((2, -1.5)\) and x-intercepts \((1, 0)\) and \((3, 0)\).

Answer

a) \(f(x) = 1.5(x - 2)^2 - 1.5\) b) \(x = 1\) and \(x = 3\) c) \(f(x) = 1.5(x - 1)(x - 3)\) d) The graph confirms vertex \((2, -1.5)\) and x-intercepts \((1, 0)\) and \((3, 0)\).
5145449
Let \(h(x) = 2x^2 - 12x + 10\). a) Complete the square to rewrite the function in vertex form. b) What is the minimum value of \(h\), and at what \(x\)-value does it occur? c) Explain without additional calculation why \(h(x) = -10\) has no real solution. d) Find the \(x\)-values for which \(h(x) = 10\). Interpret the result graphically.

Hints

- How can you factor the coefficient of \(x^2\) from the variable terms? - What does vertex form tell you about a minimum or maximum? - Use the function's range to analyze part c). - What do solutions to \(h(x) = 10\) represent on the graph?

Solution

1. Factor the leading coefficient from the variable terms and complete the square: \(h(x) = 2(x^2 - 6x) + 10 = 2(x^2 - 6x + 9 - 9) + 10 = 2(x - 3)^2 - 8\). 2. The vertex is \((3, -8)\). Because the leading coefficient is positive, the parabola opens upward, so the minimum value is \(-8\) at \(x = 3\). 3. The range is \(h(x) \geq -8\). Since \(-10 < -8\), the equation \(h(x) = -10\) has no real solution. 4. Solve \(h(x) = 10\): \(2x^2 - 12x + 10 = 10\), so \(2x^2 - 12x = 0\). Factoring gives \(2x(x - 6) = 0\), so \(x = 0\) or \(x = 6\). The graph intersects the horizontal line \(y = 10\) at \((0, 10)\) and \((6, 10)\).

Answer

a) \(h(x) = 2(x - 3)^2 - 8\) b) The minimum value is \(-8\) at \(x = 3\). c) The function never takes a value below \(-8\), so it cannot equal \(-10\). d) \(x = 0\) and \(x = 6\); the intersections with \(y = 10\) are \((0, 10)\) and \((6, 10)\).
5153009
Consider the family \(h_p(x) = x^2 - px + 9\), where \(p > 0\). Find the value of \(p\) for which the vertex lies on the \(x\)-axis.

Hints

- What must the vertex's \(y\)-coordinate be if it lies on the \(x\)-axis? - Treat \(p\) like a number while completing the square. - Which solution satisfies the condition \(p > 0\)?

Solution

1. Complete the square with the parameter: \(h_p(x) = x^2 - px + \frac{p^2}{4} - \frac{p^2}{4} + 9 = \left(x - \frac{p}{2}\right)^2 + 9 - \frac{p^2}{4}\). 2. The vertex lies on the \(x\)-axis when its \(y\)-coordinate is \(0\): \(9 - \frac{p^2}{4} = 0\). 3. Then \(p^2 = 36\), so \(p = 6\) or \(p = -6\). 4. Because \(p > 0\), the required value is \(p = 6\).

Answer

\(p = 6\)
5254509
Consider the quadratic function \(f(x) = x^2 + px + q\). a) Use completing the square to derive the coordinates of the vertex in terms of \(p\) and \(q\). b) A classmate claims, “If \(q < \left(\frac{p}{2}\right)^2\), then the parabola must cross the x-axis twice.” Determine whether the claim is true and justify your answer.

Hints

- Add and subtract the square of half the coefficient of \(x\). - Identify the vertex from the resulting vertex form. - Rewrite the claimed inequality in terms of the vertex’s y-coordinate.

Solution

1. Complete the square: \(f(x) = x^2 + px + \left(\frac{p}{2}\right)^2 - \left(\frac{p}{2}\right)^2 + q\). 2. Therefore, \(f(x) = \left(x + \frac{p}{2}\right)^2 + q - \frac{p^2}{4}\). 3. The vertex is \(\left(-\frac{p}{2}, q - \frac{p^2}{4}\right)\). 4. The condition \(q < \left(\frac{p}{2}\right)^2\) is equivalent to \(q - \frac{p^2}{4} < 0\), so the vertex lies below the x-axis. 5. Since the parabola opens upward, a vertex below the x-axis implies that the graph crosses the x-axis twice. The claim is true.

Answer

a) The vertex is \(\left(-\frac{p}{2}, q - \frac{p^2}{4}\right)\). b) The claim is true because the condition places the vertex below the x-axis while the parabola opens upward.
5250689
Derive the quadratic formula from \(ax^2 + bx + c = 0\), where \(a \ne 0\), using a form of completing the square that avoids fractions until the final steps. a) Multiply the equation by \(4a\), and then subtract \(4ac\) from both sides. b) Add \(b^2\) to both sides. Show that the left side is a perfect square, and write the resulting equation. c) Continue solving for \(x\) to obtain the quadratic formula. Explain why the perfect-square form is useful.

Hints

- View \(4a^2x^2\) as \((2ax)^2\). - Match the left side to \(A^2 + 2AB + B^2\). - After forming a square, take both square roots and isolate \(x\).

Solution

1. Multiply by \(4a\): \(4a^2x^2 + 4abx + 4ac = 0\). 2. Subtract \(4ac\): \(4a^2x^2 + 4abx = -4ac\). 3. Add \(b^2\): \(4a^2x^2 + 4abx + b^2 = b^2 - 4ac\). 4. The left side is a perfect square: \((2ax + b)^2 = b^2 - 4ac\). 5. Take both square roots: \(2ax + b = \pm\sqrt{b^2 - 4ac}\). 6. Subtract \(b\) and divide by \(2a\): \(x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\). 7. The perfect-square form is useful because it places the variable in one squared expression that can be isolated by taking square roots.

Answer

a) \(4a^2x^2 + 4abx = -4ac\) b) \((2ax + b)^2 = b^2 - 4ac\) c) \(x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\); the perfect-square form allows the equation to be solved by taking square roots.

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