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Fundamental theorem of calculus

Learning goals

  • Connects differentiation and integration through the fundamental theorem.
  • Evaluates definite integrals using antiderivatives.
  • Differentiates accumulation functions with variable limits.
  • Uses the theorem to interpret net change.

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Fundamental theorem of calculus 1
Let \(F\) be an antiderivative of \(f\), with \(F(1)=3\) and \(F(5)=11\). Find \(\int_1^5 f(x)\,\text{d}x\).

Hints

- The given function \(F\) is connected to the integrand through differentiation. - For a definite integral, compare the antiderivative values at the two endpoints in the correct order.

Solution

1. By the Fundamental Theorem of Calculus, \(\int_1^5 f(x)\,\text{d}x=F(5)-F(1)\). 2. Therefore \(\int_1^5 f(x)\,\text{d}x=11-3=8\).

Answer

\(8\)
Fundamental theorem of calculus 2
An antiderivative \(F\) satisfies \(F(2)=5\) and \(\int_2^7 f(x)\,\text{d}x=-3\), where \(F'(x)=f(x)\). Find \(F(7)\).

Hints

- Connect the integral to the change in an antiderivative. - Which endpoint value is known, and which is missing? - Use the given change to find the missing value.

Solution

1. By the Fundamental Theorem of Calculus, \(F(7)-F(2)=\int_2^7f(x)\,\text{d}x=-3\). 2. Thus \(F(7)=5-3=2\).

Answer

\(F(7)=2\)
Fundamental theorem of calculus 3
The function \(G(x)=x^3\) is an antiderivative of \(g(x)=3x^2\). A student writes \(\int_1^2g(x)\,\text{d}x=G(1)-G(2)=-7\). Find the error and give the correct integral value.

Hints

- Check how the Fundamental Theorem orders the endpoint values. - Is a negative result reasonable for this positive integrand?

Solution

1. The student subtracts the antiderivative endpoint values in the wrong order. The Fundamental Theorem gives \(\int_1^2g(x)\,\text{d}x=G(2)-G(1)\). 2. Evaluate \(2^3-1^3=8-1=7\), which is also consistent with \(g(x)>0\) on this interval.

Answer

The subtraction is reversed. The correct value is \(G(2)-G(1)=7\).
Fundamental theorem of calculus 4
Let \(H(x)=\int_0^x e^{-t^2}\,\text{d}t\). Find \(H'(x)\). You do not need an antiderivative of \(e^{-t^2}\).

Hints

- The Fundamental Theorem does not require you to write an elementary antiderivative first. - Which version of the theorem connects a changing integral with its derivative?

Solution

1. The integrand \(e^{-t^2}\) is continuous. 2. By the Fundamental Theorem of Calculus, differentiating this variable-upper-limit integral gives \(H'(x)=e^{-x^2}\).

Answer

\(H'(x)=e^{-x^2}\)
Fundamental theorem of calculus 5
Evaluate each definite integral. a) \(\int_{-2}^{4}(x+1)\,\text{d}x\) b) \(\int_{0}^{5}(2-0.8t)\,\text{d}t\) c) \(\int_{4}^{1}(1.5u-3)\,\text{d}u\)

Hints

- Find an antiderivative of each integrand. - Substitute the upper and lower limits carefully. - Pay special attention when the upper limit is less than the lower limit. - Integrate each term separately.

Solution

1. For a), an antiderivative is \(F(x)=\frac{1}{2}x^2+x\). Thus, \(F(4)-F(-2)=12-0=12\). 2. For b), an antiderivative is \(F(t)=2t-0.4t^2\). Thus, \(F(5)-F(0)=10-10=0\). 3. For c), an antiderivative is \(F(u)=0.75u^2-3u\). Thus, \(F(1)-F(4)=-2.25-0=-2.25\).

Answer

a) \(12\) b) \(0\) c) \(-2.25\)
Fundamental theorem of calculus 6
Let \(f(x)=-\frac{1}{4}x+1\). Evaluate \(I=\int_{0}^{8}f(x)\,\text{d}x\). Interpret the result as the net signed area between the graph of \(f\) and the x-axis on \([0, 8]\).

Hints

- First evaluate the integral using an antiderivative. - Find where the graph crosses the x-axis. - Identify which part of the graph lies above the axis and which part lies below it. - Interpret what an integral value of zero means about the two signed-area contributions.

Solution

1. An antiderivative of \(f(x)=-\frac{1}{4}x+1\) is \(F(x)=-\frac{1}{8}x^2+x\). Therefore, \(I=F(8)-F(0)=\left(-\frac{1}{8}\cdot 64+8\right)-0=-8+8=0\). 2. The graph crosses the x-axis at \(x=4\). On \([0, 4]\), the graph is above the axis and contributes signed area \(\int_{0}^{4}f(x)\,\text{d}x=2\). On \([4, 8]\), it is below the axis and contributes signed area \(\int_{4}^{8}f(x)\,\text{d}x=-2\). These contributions cancel, so the net signed area is \(0\).

Answer

The integral is \(I=0\). The positive area above the x-axis on \([0, 4]\) equals the magnitude of the negative area below the x-axis on \([4, 8]\), so the net signed area is zero.
Fundamental theorem of calculus 7
Evaluate each definite integral. Briefly interpret the result in part b) as a net area. a) \(\int_{-1}^{2}(x^2-2x-3)\,\text{d}x\) b) \(\int_{0}^{4}\left(\frac{1}{2}x^3-4x\right)\,\text{d}x\)

Hints

- Use the Fundamental Theorem of Calculus. - Evaluate the antiderivative at the upper limit and subtract its value at the lower limit. - Recall how portions of a graph below the x-axis contribute to a definite integral. - Consider what a net area of zero means.

Solution

1. For a), an antiderivative is \(F(x)=\frac{1}{3}x^3-x^2-3x\). Then \(F(2)=-\frac{22}{3}\) and \(F(-1)=\frac{5}{3}\), so \(F(2)-F(-1)=-\frac{22}{3}-\frac{5}{3}=-9\). 2. For b), an antiderivative is \(G(x)=\frac{1}{8}x^4-2x^2\). Since \(G(4)=0\) and \(G(0)=0\), the integral is \(0\). 3. A net area of \(0\) means that the positive and negative signed areas on \([0, 4]\) have equal magnitudes and cancel.

Answer

a) \(-9\) b) \(0\). The signed areas above and below the x-axis on \([0, 4]\) cancel.
Fundamental theorem of calculus 8
Evaluate each integral in terms of the real parameter \(a\). a) \(\int_1^2(ax^3-a)\,\text{d}x\) b) \(\int_0^1(a+1)x^2\,\text{d}x\)

Hints

- Integrate with respect to \(x\), treating \(a\) as a constant. - Use the power rule. - Apply the upper and lower bounds carefully. - Terms containing a factor of \(0\) vanish at the lower bound in b).

Solution

1. For a), an antiderivative is \(F(x)=\frac{ax^4}{4}-ax\). Therefore, \(F(2)-F(1)=2a-\left(-\frac{3a}{4}\right)=\frac{11a}{4}\). 2. For b), an antiderivative is \(G(x)=\frac{a+1}{3}x^3\). Thus, \(G(1)-G(0)=\frac{a+1}{3}\).

Answer

a) \(\frac{11a}{4}\) b) \(\frac{a+1}{3}\)
Fundamental theorem of calculus 9
Evaluate each integral in terms of the real parameter \(a\). a) \(\int_{-2}^{2}(ax^2+a^3)\,\text{d}x\) b) \(\int_1^4\frac{a}{\sqrt{x}}\,\text{d}x\)

Hints

- Rewrite the square-root denominator as a negative power. - Treat \(a\) as a constant. - Track signs carefully at the negative lower bound. - Symmetry can also simplify part a).

Solution

1. For a), an antiderivative is \(F(x)=\frac{ax^3}{3}+a^3x\). Evaluating from \(-2\) to \(2\) gives \(\frac{16a}{3}+4a^3\). 2. For b), write the integrand as \(ax^{-1/2}\). An antiderivative is \(G(x)=2a\sqrt{x}\). Therefore, \(G(4)-G(1)=4a-2a=2a\).

Answer

a) \(\frac{16a}{3}+4a^3\) b) \(2a\)
Fundamental theorem of calculus 10
Use the Fundamental Theorem of Calculus to evaluate \(\int_{1}^{4}\left(\frac{1}{2}x^2-2\right)\,\text{d}x\).

Hints

- Apply the power rule to find an antiderivative. - Use upper-limit value minus lower-limit value. - Use parentheses when subtracting a negative value. - A constant factor can remain in front while you integrate.

Solution

1. An antiderivative of \(f(x)=\frac{1}{2}x^2-2\) is \(F(x)=\frac{1}{6}x^3-2x\). 2. Evaluate at the limits: \(F(4)=\frac{64}{6}-8=\frac{8}{3}\) and \(F(1)=\frac{1}{6}-2=-\frac{11}{6}\). 3. Therefore, \(F(4)-F(1)=\frac{8}{3}-\left(-\frac{11}{6}\right)=\frac{27}{6}=\frac{9}{2}=4.5\).

Answer

\(4.5\)
Fundamental theorem of calculus 11
Use an antiderivative to evaluate \(\int_{-1}^{2}\left(\frac{1}{4}x^3+x\right)\,\text{d}x\).

Hints

- Apply the power rule term by term. - Remember how an even power affects a negative input. - Keep the result as a fraction until the final step. - Put the entire lower-limit value in parentheses when subtracting.

Solution

1. An antiderivative is \(F(x)=\frac{1}{16}x^4+\frac{1}{2}x^2\). 2. Evaluate at the limits: \(F(2)=1+2=3\) and \(F(-1)=\frac{1}{16}+\frac{1}{2}=\frac{9}{16}\). 3. Thus, \(F(2)-F(-1)=3-\frac{9}{16}=\frac{39}{16}=2.4375\).

Answer

\(\frac{39}{16}\), or \(2.4375\)
Fundamental theorem of calculus 12
Let \(k\) be a real parameter. Use the Fundamental Theorem of Calculus to evaluate \(\int_{-1}^{2}(x^3-kx)\,\text{d}x\) in terms of \(k\).

Hints

- Treat \(k\) as a constant while integrating. - Use the power rule to find an antiderivative. - Be careful with even powers at the negative lower bound. - Subtract the entire lower-bound expression.

Solution

1. An antiderivative is \(F(x)=\frac{x^4}{4}-\frac{kx^2}{2}\). 2. Evaluate the endpoints: \(F(2)=4-2k\) and \(F(-1)=\frac{1}{4}-\frac{k}{2}\). 3. Subtract: \(F(2)-F(-1)=\frac{15}{4}-\frac{3k}{2}\).

Answer

\(\frac{15}{4}-\frac{3k}{2}\)
Fundamental theorem of calculus 13
Let \(f(x)=ax^2+\frac{1}{x^2}\), where \(a\) is real. Evaluate \(\int_1^3 f(x)\,\text{d}x\) in terms of \(a\).

Hints

- Rewrite the reciprocal-square term using a negative exponent. - Treat \(a\) as a constant. - Find an antiderivative before applying the bounds. - Subtract the entire lower-bound expression.

Solution

1. Rewrite \(\frac{1}{x^2}\) as \(x^{-2}\). An antiderivative is \(F(x)=\frac{ax^3}{3}-\frac{1}{x}\). 2. Evaluate: \(F(3)=9a-\frac{1}{3}\) and \(F(1)=\frac{a}{3}-1\). 3. Subtract: \(F(3)-F(1)=\frac{26a}{3}+\frac{2}{3}\).

Answer

\(\frac{26a}{3}+\frac{2}{3}\)
Fundamental theorem of calculus 14
Evaluate \(\int_{3}^{0}(4x^3-6x^2+2x-5)\,\text{d}x\).

Hints

- Pay attention to the order of the limits. - Integrate the polynomial term by term. - Check the value of the antiderivative at \(x=3\) carefully.

Solution

1. An antiderivative is \(F(x)=x^4-2x^3+x^2-5x\). 2. The endpoint values are \(F(0)=0\) and \(F(3)=81-54+9-15=21\). 3. Because the integral runs from \(3\) to \(0\), \(F(0)-F(3)=0-21=-21\).

Answer

\(-21\)
Fundamental theorem of calculus 15
Let \(f\) be continuous and let \(F\) be an antiderivative of \(f\). Use the Fundamental Theorem of Calculus to justify why reversing the limits changes the sign of a definite integral: \(\int_a^b f(x)\,\text{d}x=-\int_b^a f(x)\,\text{d}x\).

Hints

- How do you evaluate a definite integral when an antiderivative is known? - Write each integral separately using \(F\). - Pay attention to the order of the limits when substituting into \(F\). - What happens to every sign inside brackets preceded by a minus sign?

Solution

1. By the Fundamental Theorem of Calculus, \(\int_a^b f(x)\,\text{d}x=F(b)-F(a)\). 2. Reversing the limits gives \(\int_b^a f(x)\,\text{d}x=F(a)-F(b)\). 3. Therefore, \(-\int_b^a f(x)\,\text{d}x=-[F(a)-F(b)]=F(b)-F(a)\), which equals \(\int_a^b f(x)\,\text{d}x\).

Answer

The Fundamental Theorem of Calculus gives \(\int_a^b f(x)\,\text{d}x=F(b)-F(a)\) and \(-\int_b^a f(x)\,\text{d}x=-[F(a)-F(b)]=F(b)-F(a)\). Thus the two expressions are equal.
Fundamental theorem of calculus 16
Use the Fundamental Theorem of Calculus to find the exact value of \(\int_{1}^{4}\left(\frac{3}{2}\sqrt{x}+\frac{2}{x^2}\right)\,\text{d}x\).

Hints

- Rewrite the radical and the fraction using rational and negative exponents. - Apply the power rule to find an antiderivative. - Evaluate at the upper limit and subtract the value at the lower limit. - Be careful when subtracting a negative endpoint value.

Solution

1. Rewrite the integrand as \(\frac{3}{2}x^{1/2}+2x^{-2}\). 2. An antiderivative is \(F(x)=x^{3/2}-2x^{-1}=x\sqrt{x}-\frac{2}{x}\). 3. Evaluate: \(F(4)=8-\frac{1}{2}=\frac{15}{2}\) and \(F(1)=1-2=-1\). 4. Thus, \(F(4)-F(1)=\frac{15}{2}-(-1)=\frac{17}{2}\).

Answer

\(\frac{17}{2}\), or \(8.5\)
Fundamental theorem of calculus 17
Find the exact value of \(\int_{0}^{\pi}\left(\sin(x)-\frac{1}{3}e^x\right)\,\text{d}x\).

Hints

- Recall antiderivatives of sine and the exponential function. - Use the exact sine and cosine values at \(0\) and \(\pi\). - Recall that \(e^0=1\). - Subtract the entire lower-limit value carefully.

Solution

1. An antiderivative is \(F(x)=-\cos(x)-\frac{1}{3}e^x\). 2. At the upper limit, \(F(\pi)=1-\frac{1}{3}e^{\pi}\). 3. At the lower limit, \(F(0)=-1-\frac{1}{3}=-\frac{4}{3}\). 4. Therefore, \(F(\pi)-F(0)=1-\frac{1}{3}e^{\pi}+\frac{4}{3}=\frac{7-e^{\pi}}{3}\).

Answer

\(\frac{7-e^{\pi}}{3}\)
Fundamental theorem of calculus 18
Evaluate \(\int_{1}^{4}\left(\frac{1}{\sqrt{x}}+\frac{2}{x^2}\right)\,\text{d}x\).

Hints

- Rewrite the radical and fraction using exponents. - Use the power rule to find an antiderivative. - Evaluate the antiderivative at the upper and lower limits. - Subtract the lower-limit value from the upper-limit value.

Solution

1. Rewrite the integrand as \(x^{-1/2}+2x^{-2}\). 2. An antiderivative is \(F(x)=2x^{1/2}-2x^{-1}=2\sqrt{x}-\frac{2}{x}\). 3. Evaluate: \(F(4)=4-\frac{1}{2}=\frac{7}{2}\) and \(F(1)=2-2=0\). 4. Therefore, \(F(4)-F(1)=\frac{7}{2}\).

Answer

\(\frac{7}{2}\), or \(3.5\)
Fundamental theorem of calculus 19
Evaluate \(\int_{0}^{\frac{\pi}{2}}(3\sin(x)-2\cos(x))\,\text{d}x\).

Hints

- Recall which antiderivatives produce sine and cosine, including their signs. - Use the exact trigonometric values at \(0\) and \(\frac{\pi}{2}\). - Apply upper-limit value minus lower-limit value.

Solution

1. An antiderivative is \(F(x)=-3\cos(x)-2\sin(x)\). 2. At the upper limit, \(F\left(\frac{\pi}{2}\right)=-3\cdot 0-2\cdot 1=-2\). 3. At the lower limit, \(F(0)=-3\cdot 1-2\cdot 0=-3\). 4. Therefore, \(F\left(\frac{\pi}{2}\right)-F(0)=-2-(-3)=1\).

Answer

\(1\)
Fundamental theorem of calculus 20
Use the Fundamental Theorem of Calculus to find each exact value. a) \(\int_{-2}^{2}\left(\frac{1}{4}x^3-x\right)\,\text{d}x\) b) \(\int_{0}^{\ln(2)}e^{3x}\,\text{d}x\) c) \(\int_{0}^{\frac{\pi}{2}}(2\sin(x)-\cos(2x))\,\text{d}x\)

Hints

- In part a), consider the symmetry of the integrand. - For a linear expression in an exponent or angle, account for its derivative when finding an antiderivative. - Check signs carefully when integrating sine and cosine. - Use exponent and logarithm properties to simplify part b).

Solution

1. For a), an antiderivative is \(F(x)=\frac{1}{16}x^4-\frac{1}{2}x^2\). Because \(F(2)=F(-2)=-1\), the integral is \(0\). 2. For b), an antiderivative is \(F(x)=\frac{1}{3}e^{3x}\). Therefore, \(F(\ln(2))-F(0)=\frac{1}{3}e^{3\ln(2)}-\frac{1}{3}=\frac{8}{3}-\frac{1}{3}=\frac{7}{3}\). 3. For c), an antiderivative is \(F(x)=-2\cos(x)-\frac{1}{2}\sin(2x)\). Thus, \(F\left(\frac{\pi}{2}\right)-F(0)=0-(-2)=2\).

Answer

a) \(0\) b) \(\frac{7}{3}\) c) \(2\)
Fundamental theorem of calculus 21
Use the Fundamental Theorem of Calculus to evaluate each integral. a) \(\int_{0}^{\frac{\pi}{2}}(2\cos(x)-\sin(x))\,\text{d}x\) b) \(\int_{1}^{2}\left(\frac{4}{x^3}+2\right)\,\text{d}x\) c) \(\int_{0}^{1}(e^{2x}+x)\,\text{d}x\)

Hints

- Recall antiderivative rules for powers, exponential functions, and trigonometric functions. - Evaluate the antiderivative at the upper limit and subtract its value at the lower limit. - In part b), rewrite the fraction using a negative exponent. - In part c), account for the coefficient in the exponent.

Solution

1. For a), an antiderivative is \(F(x)=2\sin(x)+\cos(x)\). Thus, \(F\left(\frac{\pi}{2}\right)-F(0)=2-1=1\). 2. For b), an antiderivative is \(F(x)=-2x^{-2}+2x=-\frac{2}{x^2}+2x\). Thus, \(F(2)-F(1)=\frac{7}{2}-0=\frac{7}{2}\). 3. For c), an antiderivative is \(F(x)=\frac{1}{2}e^{2x}+\frac{1}{2}x^2\). Thus, \(F(1)-F(0)=\left(\frac{1}{2}e^2+\frac{1}{2}\right)-\frac{1}{2}=\frac{1}{2}e^2\).

Answer

a) \(1\) b) \(\frac{7}{2}\) c) \(\frac{1}{2}e^2\)
Fundamental theorem of calculus 22
Evaluate each integral. a) \(\int_{1}^{4}(3\sqrt{x}-1)\,\text{d}x\) b) \(\int_{e}^{e^2}\frac{2}{x}\,\text{d}x\) c) \(\int_{-1}^{1}(x^5-3x^2)\,\text{d}x\)

Hints

- Rewrite the radical as a power before using the power rule. - Recall the antiderivative of \(\frac{1}{x}\). - Use parentheses when substituting negative values into powers. - In part c), symmetry can simplify part of the integral.

Solution

1. For a), rewrite the integrand as \(3x^{1/2}-1\). An antiderivative is \(F(x)=2x^{3/2}-x\). Therefore, \(F(4)-F(1)=12-1=11\). 2. For b), an antiderivative is \(F(x)=2\ln(x)\) on the interval. Thus, \(F(e^2)-F(e)=4-2=2\). 3. For c), an antiderivative is \(F(x)=\frac{1}{6}x^6-x^3\). Therefore, \(F(1)-F(-1)=-\frac{5}{6}-\frac{7}{6}=-2\).

Answer

a) \(11\) b) \(2\) c) \(-2\)
Fundamental theorem of calculus 23
Let \(g(x)=\frac{2}{x}+\frac{6}{x^2}\) for \(x>0\). a) Find an antiderivative \(G\) of \(g\). b) Use the Fundamental Theorem of Calculus to evaluate \(\int_{1}^{e}g(x)\,\text{d}x\).

Hints

- Rewrite the second fraction using a negative exponent. - The power rule does not apply to \(x^{-1}\); use a logarithm for that term. - Apply the Fundamental Theorem of Calculus using the two limits. - Recall the values of \(\ln(e)\) and \(\ln(1)\).

Solution

1. Rewrite \(g(x)=\frac{2}{x}+6x^{-2}\). 2. An antiderivative is \(G(x)=2\ln(x)-6x^{-1}=2\ln(x)-\frac{6}{x}\). 3. Apply the Fundamental Theorem of Calculus: \(\int_{1}^{e}g(x)\,\text{d}x=G(e)-G(1)\). 4. Since \(G(e)=2-\frac{6}{e}\) and \(G(1)=-6\), the value is \(2-\frac{6}{e}-(-6)=8-\frac{6}{e}\).

Answer

a) \(G(x)=2\ln(x)-\frac{6}{x}\) b) \(8-\frac{6}{e}\)
Fundamental theorem of calculus 24
Evaluate \(\int_{-1}^{2}(6x^2-2x+1)\,\text{d}x\). Show how you find an antiderivative and apply the Fundamental Theorem of Calculus.

Hints

- Apply the power rule to each term. - Use the Fundamental Theorem of Calculus to connect the antiderivative and the definite integral. - Use parentheses and check signs carefully when substituting the negative lower limit.

Solution

1. Using the power, sum, and constant multiple rules, an antiderivative is \(F(x)=2x^3-x^2+x\). 2. Evaluate the endpoint values: \(F(2)=16-4+2=14\) and \(F(-1)=-2-1-1=-4\). 3. Therefore, \(F(2)-F(-1)=14-(-4)=18\).

Answer

\(18\)
Fundamental theorem of calculus 25
Evaluate \(\int_{0}^{4}\left(\frac{1}{8}x^3+\frac{3}{2}x^2-4\right)\,\text{d}x\). State the integration rules you use to find an antiderivative.

Hints

- Integrate the sum term by term. - Keep each constant multiple when applying the power rule. - Differentiate your antiderivative mentally to check that it gives the original integrand.

Solution

1. Using the power, sum, and constant multiple rules, an antiderivative is \(F(x)=\frac{1}{32}x^4+\frac{1}{2}x^3-4x\). 2. Evaluate: \(F(4)=8+32-16=24\) and \(F(0)=0\). 3. Therefore, \(F(4)-F(0)=24\).

Answer

\(24\). The antiderivative uses the power rule, constant multiple rule, and sum rule.
Fundamental theorem of calculus 26
The variable of integration does not have to be \(x\). Evaluate \(\int_{1}^{2}(6u^2-4u+3)\,\text{d}u\), and name the integration rules you use.

Hints

- Identify the variable named in the differential. - Integrate the polynomial term by term. - Evaluate the antiderivative at both limits. - Use the Fundamental Theorem of Calculus to subtract the endpoint values.

Solution

1. Using the power, constant multiple, and sum rules, an antiderivative is \(F(u)=2u^3-2u^2+3u\). 2. Evaluate: \(F(2)=16-8+6=14\) and \(F(1)=2-2+3=3\). 3. By the Fundamental Theorem of Calculus, \(F(2)-F(1)=14-3=11\).

Answer

The integral is \(11\). The rules used are the power rule, constant multiple rule, sum rule, and the Fundamental Theorem of Calculus.
Fundamental theorem of calculus 27
Evaluate \(\int_{-1}^{2}(v^3-v)\,\text{d}v\), state the rules you use, and pay close attention to the signs at the limits.

Hints

- Use parentheses when substituting the negative lower limit. - Apply the power rule to each term. - Use the difference rule for the two terms. - Subtract the lower-limit value from the upper-limit value.

Solution

1. Using the power and difference rules, an antiderivative is \(F(v)=\frac{1}{4}v^4-\frac{1}{2}v^2\). 2. Evaluate: \(F(2)=4-2=2\) and \(F(-1)=\frac{1}{4}-\frac{1}{2}=-\frac{1}{4}\). 3. By the Fundamental Theorem of Calculus, \(F(2)-F(-1)=2-\left(-\frac{1}{4}\right)=\frac{9}{4}\).

Answer

The integral is \(\frac{9}{4}\), or \(2.25\). The rules used are the power rule, difference rule, and the Fundamental Theorem of Calculus.
Fundamental theorem of calculus 28
Use the Fundamental Theorem of Calculus to evaluate \(\int_{0}^{4}(3t^2-2t)\,\text{d}t\).

Hints

- Use the power rule to find an antiderivative. - Substitute the upper limit first. - Evaluate the lower-limit value and subtract it.

Solution

1. An antiderivative is \(F(t)=t^3-t^2\). 2. Evaluate: \(F(4)=64-16=48\) and \(F(0)=0\). 3. Therefore, \(F(4)-F(0)=48\).

Answer

\(48\)
Fundamental theorem of calculus 29
Evaluate \(\int_{-1}^{2}\left(\frac{1}{2}x^3-3x+1\right)\,\text{d}x\).

Hints

- Integrate the polynomial term by term. - Use parentheses when substituting the negative lower limit. - Recall that an even power of a negative number is positive. - Keep exact fractions until the final step.

Solution

1. An antiderivative is \(F(x)=\frac{1}{8}x^4-\frac{3}{2}x^2+x\). 2. Evaluate at the upper limit: \(F(2)=2-6+2=-2\). 3. Evaluate at the lower limit: \(F(-1)=\frac{1}{8}-\frac{3}{2}-1=-\frac{19}{8}\). 4. Therefore, \(F(2)-F(-1)=-2+\frac{19}{8}=\frac{3}{8}\).

Answer

\(\frac{3}{8}\), or \(0.375\)
Fundamental theorem of calculus 30
Use the Fundamental Theorem of Calculus to evaluate \(\int_{0}^{\sqrt{6}}\left(\frac{1}{3}x^3-2x\right)\,\text{d}x\).

Hints

- Use the power rule to find an antiderivative. - Simplify powers of \(\sqrt{6}\) carefully. - Subtract the lower-limit value from the upper-limit value.

Solution

1. An antiderivative is \(F(x)=\frac{1}{12}x^4-x^2\). 2. At the upper limit, \(F(\sqrt{6})=\frac{1}{12}(\sqrt{6})^4-(\sqrt{6})^2=3-6=-3\). 3. Since \(F(0)=0\), the integral is \(F(\sqrt{6})-F(0)=-3\).

Answer

\(-3\)
Fundamental theorem of calculus 31
Evaluate each definite integral. a) \(\int_{1}^{4}(x^2-4x+6)\,\text{d}x\) b) \(\int_{-2}^{2}(x^3-3x)\,\text{d}x\)

Hints

- Apply the Fundamental Theorem of Calculus. - Use the power rule to find each antiderivative. - Check signs carefully at a negative lower limit. - In part b), consider the symmetry of the integrand and interval.

Solution

1. For a), an antiderivative is \(F(x)=\frac{1}{3}x^3-2x^2+6x\). Since \(F(4)=\frac{40}{3}\) and \(F(1)=\frac{13}{3}\), the integral is \(9\). 2. For b), an antiderivative is \(G(x)=\frac{1}{4}x^4-\frac{3}{2}x^2\). Since \(G(2)=G(-2)=-2\), the integral is \(0\).

Answer

a) \(9\) b) \(0\)
Fundamental theorem of calculus 32
Evaluate each integral. a) \(\int_{0}^{3}\left(\frac{1}{3}x^3-x^2+2\right)\,\text{d}x\) b) \(\int_{-1}^{2}(6x^2-2x-4)\,\text{d}x\)

Hints

- Find an antiderivative before substituting the limits. - When integrating \(x^n\), increase the exponent by one and divide by the new exponent. - Put the lower-limit value in parentheses when subtracting.

Solution

1. For a), an antiderivative is \(F(x)=\frac{1}{12}x^4-\frac{1}{3}x^3+2x\). Then \(F(3)-F(0)=\frac{15}{4}-0=\frac{15}{4}\). 2. For b), an antiderivative is \(G(x)=2x^3-x^2-4x\). Since \(G(2)=4\) and \(G(-1)=1\), the integral is \(3\).

Answer

a) \(\frac{15}{4}\), or \(3.75\) b) \(3\)
Fundamental theorem of calculus 33
Evaluate \(\int_{0}^{\frac{\pi}{2}}(3\cos(x)-2x)\,\text{d}x\).

Hints

- Recall the antiderivative of cosine and use the power rule for \(x\). - Use radians for the trigonometric limit. - Subtract the lower-limit value from the upper-limit value.

Solution

1. An antiderivative is \(F(x)=3\sin(x)-x^2\). 2. At the upper limit, \(F\left(\frac{\pi}{2}\right)=3-\frac{\pi^2}{4}\). 3. Since \(F(0)=0\), the integral is \(3-\frac{\pi^2}{4}\).

Answer

\(3-\frac{\pi^2}{4}\)
Fundamental theorem of calculus 34
Evaluate \(\int_{1}^{4}\left(3x^2-\frac{4}{x^2}+\sqrt{x}\right)\,\text{d}x\).

Hints

- Rewrite the fraction and radical using negative and rational exponents. - Apply the power rule term by term. - Evaluate each endpoint carefully. - Use the Fundamental Theorem of Calculus.

Solution

1. Rewrite the integrand as \(3x^2-4x^{-2}+x^{1/2}\). 2. An antiderivative is \(F(x)=x^3+4x^{-1}+\frac{2}{3}x^{3/2}\). 3. Evaluate: \(F(4)=64+1+\frac{16}{3}=\frac{211}{3}\), and \(F(1)=1+4+\frac{2}{3}=\frac{17}{3}\). 4. Therefore, \(F(4)-F(1)=\frac{194}{3}\).

Answer

\(\frac{194}{3}\), or \(64\frac{2}{3}\)
Fundamental theorem of calculus 35
Use the Fundamental Theorem of Calculus to evaluate each integral. a) \(\int_{0}^{3}(x^2-2)\,\text{d}x\) b) \(\int_{1}^{4}\frac{1}{\sqrt{x}}\,\text{d}x\) c) \(\int_{-2}^{2}x^3\,\text{d}x\)

Hints

- Apply the power rule to find antiderivatives. - Integrate sums and differences term by term. - Rewrite the radical as a rational power. - For part c), consider the symmetry of an odd function on a symmetric interval.

Solution

1. For a), an antiderivative is \(F(x)=\frac{1}{3}x^3-2x\). Thus, \(F(3)-F(0)=3\). 2. For b), rewrite the integrand as \(x^{-1/2}\). An antiderivative is \(F(x)=2\sqrt{x}\). Thus, \(F(4)-F(1)=4-2=2\). 3. For c), an antiderivative is \(F(x)=\frac{1}{4}x^4\). Thus, \(F(2)-F(-2)=4-4=0\).

Answer

a) \(3\) b) \(2\) c) \(0\)
Fundamental theorem of calculus 36
Evaluate each definite integral. a) \(\int_{1}^{2}\frac{3}{x^4}\,\text{d}x\) b) \(\int_{1}^{4}(x+\sqrt{x})\,\text{d}x\) c) \(\int_{0}^{2}(x^3-x)\,\text{d}x\)

Hints

- Rewrite reciprocal powers using negative exponents. - Treat \(\sqrt{x}\) as \(x^{1/2}\). - Apply the power rule term by term. - Check signs carefully when subtracting a negative antiderivative value.

Solution

1. For a), rewrite the integrand as \(3x^{-4}\). An antiderivative is \(F(x)=-x^{-3}\). Thus, \(F(2)-F(1)=-\frac{1}{8}-(-1)=\frac{7}{8}\). 2. For b), an antiderivative is \(F(x)=\frac{1}{2}x^2+\frac{2}{3}x^{3/2}\). Thus, \(F(4)-F(1)=\frac{40}{3}-\frac{7}{6}=\frac{73}{6}\). 3. For c), an antiderivative is \(F(x)=\frac{1}{4}x^4-\frac{1}{2}x^2\). Thus, \(F(2)-F(0)=2\).

Answer

a) \(\frac{7}{8}\) b) \(\frac{73}{6}\) c) \(2\)
Fundamental theorem of calculus 37
Evaluate \(\int_{1}^{4}\left(\frac{3}{2\sqrt{t}}-\frac{2}{t^2}\right)\,\text{d}t\).

Hints

- Rewrite radicals and reciprocals using rational and negative exponents. - Integrate each term separately. - Check the signs produced by the power rule for negative exponents. - Differentiate your antiderivative to verify it before using the limits.

Solution

1. Rewrite the integrand as \(\frac{3}{2}t^{-1/2}-2t^{-2}\). 2. An antiderivative is \(F(t)=3t^{1/2}+2t^{-1}=3\sqrt{t}+\frac{2}{t}\). 3. Evaluate: \(F(4)=6+\frac{1}{2}=\frac{13}{2}\), and \(F(1)=3+2=5\). 4. Therefore, \(F(4)-F(1)=\frac{3}{2}\).

Answer

\(\frac{3}{2}\), or \(1.5\)
Fundamental theorem of calculus 38
Use the Fundamental Theorem of Calculus to evaluate \(\int_{-1}^{2}(4x^3-6x^2+2)\,\text{d}x\).

Hints

- Use the relationship between a definite integral and an antiderivative. - Apply the power rule term by term. - Use parentheses when substituting the negative lower limit. - Interpret \([F(x)]_a^b\) as \(F(b)-F(a)\).

Solution

1. An antiderivative is \(F(x)=x^4-2x^3+2x\). 2. Evaluate: \(F(2)=16-16+4=4\), and \(F(-1)=1+2-2=1\). 3. Therefore, \(F(2)-F(-1)=4-1=3\).

Answer

\(3\)
Fundamental theorem of calculus 39
Use the sum rule and the Fundamental Theorem of Calculus to evaluate \(\int_0^1(e^x+3x^2)\,\text{d}x\). Then explain why this value also equals the geometric area between the graph of \(e^x+3x^2\) and the x-axis on \([0, 1]\).

Hints

- Split the integral into the sum of two simpler integrals. - Find one antiderivative by integrating each term separately. - Evaluate at \(1\) and \(0\). - Check the sign of the integrand before interpreting the result as geometric area.

Solution

1. By the sum rule, \(\int_0^1(e^x+3x^2)\,\text{d}x=\int_0^1e^x\,\text{d}x+\int_0^1 3x^2\,\text{d}x\). 2. An antiderivative of the full integrand is \(F(x)=e^x+x^3\). Therefore, the integral is \(F(1)-F(0)=(e+1)-1=e\). 3. Since \(e^x+3x^2>0\) throughout \([0, 1]\), the definite integral has no negative signed-area contribution. Thus, its value is also the geometric area between the graph and the x-axis.

Answer

The integral equals \(e\). Because the integrand is positive on \([0, 1]\), the corresponding geometric area is also \(e\) square units.
Fundamental theorem of calculus 40
Use an appropriate antiderivative to evaluate \(\int_{1}^{3}(3x^2-4x+1)\,\text{d}x\).

Hints

- Apply the power rule to each polynomial term. - Evaluate the antiderivative at both limits. - Subtract the lower-limit value from the upper-limit value.

Solution

1. An antiderivative is \(F(x)=x^3-2x^2+x\). 2. Evaluate: \(F(3)=27-18+3=12\), and \(F(1)=1-2+1=0\). 3. Therefore, \(F(3)-F(1)=12\).

Answer

\(12\)
Fundamental theorem of calculus 41
A continuous function \(f\) has the antiderivative \(F(x)=(x-2)e^x\). Use the Fundamental Theorem of Calculus directly to evaluate \(\int_{0}^{2}f(x)\,\text{d}x\).

Hints

- Use the Fundamental Theorem of Calculus with the given antiderivative. - You do not need to find an explicit formula for \(f\). - Recall that \(e^0=1\), and check the sign of the lower-limit value.

Solution

1. Since \(F\) is already given as an antiderivative, \(\int_{0}^{2}f(x)\,\text{d}x=F(2)-F(0)\). 2. Evaluate: \(F(2)=(2-2)e^2=0\), and \(F(0)=(0-2)e^0=-2\). 3. Therefore, \(F(2)-F(0)=0-(-2)=2\).

Answer

\(2\)
Fundamental theorem of calculus 42
Find the exact value of \(\int_{1}^{e^2}\left(\frac{5}{x}-1\right)\,\text{d}x\).

Hints

- Recall which function has derivative \(\frac{1}{x}\). - Find the antiderivative term by term. - Apply the Fundamental Theorem of Calculus. - Simplify \(\ln(e^k)\) using logarithm properties.

Solution

1. On this positive interval, an antiderivative is \(F(x)=5\ln(x)-x\). 2. Evaluate: \(F(e^2)=5\ln(e^2)-e^2=10-e^2\), and \(F(1)=5\ln(1)-1=-1\). 3. Therefore, \(F(e^2)-F(1)=10-e^2-(-1)=11-e^2\).

Answer

\(11-e^2\)
Fundamental theorem of calculus 43
Use the Fundamental Theorem of Calculus to find each exact value. a) \(\int_{-e^2}^{-e}\frac{5}{x}\,\text{d}x\) b) \(\int_{0.5}^{2}\frac{1}{2x}\,\text{d}x\)

Hints

- Recall the general antiderivative of \(\frac{1}{x}\). - Keep the absolute value when logarithms involve negative limits. - Use logarithm properties to simplify the results. - Recall the values of \(\ln(e)\) and \(\ln(e^k)\).

Solution

1. For a), an antiderivative is \(F(x)=5\ln|x|\). Thus, \(F(-e)-F(-e^2)=5\ln(e)-5\ln(e^2)=5-10=-5\). 2. For b), an antiderivative is \(G(x)=\frac{1}{2}\ln|x|\). Thus, \(G(2)-G(0.5)=\frac{1}{2}\ln(2)-\frac{1}{2}\ln\left(\frac{1}{2}\right)=\ln(2)\).

Answer

a) \(-5\) b) \(\ln(2)\)
Fundamental theorem of calculus 44
Find the exact value of \(\int_{0}^{4}\left(\frac{1}{2}e^{0.25x}+2\right)\,\text{d}x\).

Hints

- Find an antiderivative for each term. - Account for the coefficient in the exponent when integrating \(e^{kx}\). - Evaluate at the upper and lower limits. - Recall that \(e^0=1\).

Solution

1. An antiderivative is \(F(x)=2e^{0.25x}+2x\), because differentiating \(2e^{0.25x}\) gives \(\frac{1}{2}e^{0.25x}\). 2. Evaluate: \(F(4)=2e+8\), and \(F(0)=2\). 3. Therefore, \(F(4)-F(0)=2e+6\).

Answer

\(2e+6\)
Fundamental theorem of calculus 45
The graph of a function \(f\) is labeled \(f\), and the graph of one of its antiderivatives is labeled \(F\). Use the graph of \(F\) to evaluate \(\int_{0}^{2}f(x)\,\text{d}x\).
Figure for problem 532697

Hints

- Relate the definite integral of \(f\) to values of its antiderivative \(F\). - Read \(F(0)\) and \(F(2)\) from the curve labeled \(F\). - Compute the upper-endpoint value minus the lower-endpoint value.

Solution

1. By the Fundamental Theorem of Calculus, \(\int_{0}^{2}f(x)\,\text{d}x=F(2)-F(0)\). 2. From the graph labeled \(F\), \(F(2)=0\) and \(F(0)=2\). 3. Therefore, \(F(2)-F(0)=0-2=-2\).

Answer

\(-2\)
Fundamental theorem of calculus 46
The graph of a linear function \(f\) is shown. Use the relationship between a definite integral and signed area to find \(F(4)-F(1)\) for any antiderivative \(F\) of \(f\).
Figure for problem 534432

Hints

- Use \(F(b)-F(a)=\int_a^b f(x)\,\text{d}x\). - Break the region into simple geometric shapes. - Areas below the x-axis count negatively.

Solution

1. By the Fundamental Theorem of Calculus, \(F(4)-F(1)=\int_1^4 f(x)\,\text{d}x\). 2. From \(x=1\) to \(x=3\), the graph forms a triangle above the x-axis with base \(2\) and height \(2\), so its area is \(\frac{1}{2}\cdot 2\cdot 2=2\). 3. From \(x=3\) to \(x=4\), the graph forms a triangle below the x-axis with base \(1\) and height \(1\), so its signed area is \(-\frac{1}{2}\). 4. Therefore, \(F(4)-F(1)=2-\frac{1}{2}=\frac{3}{2}\).

Answer

\(F(4)-F(1)=\frac{3}{2}\)
Fundamental theorem of calculus 47
The graph of \(f\) is shown. For a particular antiderivative \(F\), \(F(0)=1\). Use the graph to decide whether \(F(3)\) is greater than or less than \(1\). Justify your answer.
Figure for problem 534574

Hints

- Use \(F(3)-F(0)=\int_0^3 f(x)\,\text{d}x\). - Determine the sign of the signed area under \(f\) on \([0, 3]\). - Positive values of \(f\) make an antiderivative increase.

Solution

1. By the Fundamental Theorem of Calculus, \(F(3)=F(0)+\int_0^3 f(x)\,\text{d}x\). 2. The graph of \(f\) is above the x-axis on \([0, 3)\) and equals \(0\) at \(x=3\). Therefore, \(\int_0^3 f(x)\,\text{d}x>0\). 3. Thus, \(F(3)=1+\int_0^3 f(x)\,\text{d}x>1\).

Answer

\(F(3)>1\)
Fundamental theorem of calculus 48
Evaluate each definite integral exactly. a) \(\int_{-4}^{6}0.5\,\text{d}x\) b) \(\int_{0}^{4}(3-x)\,\text{d}x\) c) \(\int_{-2}^{3}(2t+1)\,\text{d}t\)

Hints

- Find an antiderivative for each integrand. - Apply the Fundamental Theorem of Calculus as endpoint subtraction. - Keep track of the sign when substituting a negative lower bound.

Solution

1. For a), an antiderivative is \(F(x)=0.5x\). Thus \(F(6)-F(-4)=3-(-2)=5\). 2. For b), an antiderivative is \(F(x)=3x-\frac{1}{2}x^2\). Thus \(F(4)-F(0)=12-8=4\). 3. For c), an antiderivative is \(F(t)=t^2+t\). Thus \(F(3)-F(-2)=12-2=10\).

Answer

a) \(5\) b) \(4\) c) \(10\)
Fundamental theorem of calculus 49
The graphs of a function \(f\) and one of its antiderivatives \(g\) are shown. Use the graph of \(g\) to find \(\int_0^3 f(x)\,\text{d}x\).
Figure for problem 534663

Hints

- Use the graph of the antiderivative \(g\), not the graph of \(f\). - Read \(g(3)\) and \(g(0)\). - Apply the Fundamental Theorem of Calculus.

Solution

1. By the Fundamental Theorem of Calculus, \(\int_0^3 f(x)\,\text{d}x=g(3)-g(0)\). 2. From the graph, \(g(3)=4\) and \(g(0)=1\). 3. Therefore, \(\int_0^3 f(x)\,\text{d}x=4-1=3\).

Answer

\(3\)
Fundamental theorem of calculus 50
The graph of \(f'\) is shown, and \(f(2)=6\). Use signed area and the Fundamental Theorem to find the earlier value \(f(0)\).
Figure for problem 562572

Hints

- The signed area under a derivative graph gives the difference between function values. - Consider which side of the x-axis the region lies on. - Use the signed change to work backward to the earlier value.

Solution

1. The region between \(f'\) and the x-axis from \(0\) to \(2\) is a trapezoid with heights \(1\) and \(3\), and width \(2\). It lies below the x-axis. 2. Its signed area is \(\int_0^2 f'(x)\,\text{d}x=-\frac{1+3}{2}\cdot2=-4\). 3. Since \(f(2)-f(0)=-4\) and \(f(2)=6\), the earlier value is \(f(0)=10\).

Answer

\(f(0)=10\)
Fundamental theorem of calculus 51
Find the real value of \(k\) that satisfies \(\int_1^3(kx+1)\,\text{d}x=10\).

Hints

- Treat \(k\) as a constant while integrating. - Find an antiderivative first. - Apply the bounds and form an equation in \(k\). - Solve the resulting linear equation.

Solution

1. An antiderivative is \(F(x)=\frac{kx^2}{2}+x\). 2. Apply the Fundamental Theorem: \(F(3)-F(1)=\left(\frac{9k}{2}+3\right)-\left(\frac{k}{2}+1\right)=4k+2\). 3. Set the result equal to \(10\): \(4k+2=10\), so \(k=2\).

Answer

\(k=2\)
Fundamental theorem of calculus 52
Find the derivative of each function. a) \(I(x)=\int_{x}^{10}\cos(z^2)\,\text{d}z\) b) \(A(u)=\int_{-2}^{u}\frac{e^s}{s+3}\,\text{d}s\), for \(u>-3\) c) \(F(y)=\int_{0}^{y}k\sin(x)\,\text{d}x\), where \(k\in\mathbb{R}\)

Hints

- Identify the function variable and the dummy variable of integration. - Reversing the limits changes the sign of an integral. - Apply the Fundamental Theorem of Calculus at the variable upper limit.

Solution

1. For a), reverse the limits: \(I(x)=-\int_{10}^{x}\cos(z^2)\,\text{d}z\). Therefore, \(\frac{dI}{dx}=-\cos(x^2)\). 2. For b), the Fundamental Theorem of Calculus gives \(\frac{dA}{du}=\frac{e^u}{u+3}\). 3. For c), treat \(k\) as a constant. Then \(\frac{dF}{dy}=k\sin(y)\).

Answer

a) \(\frac{dI}{dx}=-\cos(x^2)\) b) \(\frac{dA}{du}=\frac{e^u}{u+3}\) c) \(\frac{dF}{dy}=k\sin(y)\)
Fundamental theorem of calculus 53
Three students evaluate \(\int_{-1}^{2}(2-3x^2)\,\text{d}x\) and obtain different results. Luke: \((2\cdot 2-2^3)-(2\cdot(-1)-(-1)^3)=-4-(-1)=-3\) Maya: \((2\cdot(-1)-(-1)^3)-(2\cdot 2-2^3)=-1-(-4)=3\) Tom: \((2\cdot 2-2^3)-(2\cdot(-1)-1^3)=-4-(-3)=-1\) Determine who evaluated the integral correctly. For each of the other two students, describe the mathematical error.

Hints

- First verify the antiderivative. - Check the required order for subtracting endpoint values. - Use parentheses when substituting a negative number. - Review how an odd power affects a negative number.

Solution

1. An antiderivative is \(F(x)=2x-x^3\). 2. The endpoint values are \(F(2)=4-8=-4\) and \(F(-1)=-2-(-1)=-1\). 3. Therefore, \(F(2)-F(-1)=-4-(-1)=-3\), so Luke is correct. 4. Maya reversed the order of subtraction and computed \(F(-1)-F(2)\). 5. Tom substituted \(1^3\) instead of \((-1)^3\) at the lower limit, causing a sign error.

Answer

Luke is correct. Maya reversed the limits by computing \(F(-1)-F(2)\) instead of \(F(2)-F(-1)\). Tom used \(1^3\) instead of \((-1)^3\) when substituting the lower limit.
Fundamental theorem of calculus 54
Ximena evaluates \(\int_{-2}^{-1}\frac{4}{x^3}\,\text{d}x\) as follows: 1. \(\int_{-2}^{-1}4x^{-3}\,\text{d}x\) 2. \(\left[-2x^{-2}\right]_{-2}^{-1}\) 3. \((-2\cdot(-1)^{-2})-(-2\cdot(-2)^{-2})\) 4. \((-2\cdot1)-(-2\cdot4)\) 5. \(-2+8=6\) Identify the first incorrect step. Correct the work from that point and give the value of the integral.

Hints

- Check each transformation separately. - Rewrite the negative exponent using a reciprocal before evaluating. - Pay close attention to both the negative base and the negative exponent. - After evaluating the antiderivative, compare its values at the two bounds in the correct order.

Solution

1. Steps 1 through 3 are correct. The integrand is \(4x^{-3}\), and an antiderivative is \(-2x^{-2}\). 2. The first error is in step 4. Ximena used \((-2)^{-2}=4\), but \((-2)^{-2}=\frac{1}{(-2)^2}=\frac14\). 3. Correcting the endpoint values gives \(F(-1)=-2\cdot1=-2\) and \(F(-2)=-2\cdot\frac14=-\frac12\). 4. Therefore, \(F(-1)-F(-2)=-2-\left(-\frac12\right)=-\frac32\).

Answer

The first error occurs in step 4 because \((-2)^{-2}=\frac14\), not \(4\). The corrected value is \(-\frac32\), or \(-1.5\).
Fundamental theorem of calculus 55
Evaluate \(\int_{-2}^{1}(x-2)^2(x+1)\,\text{d}x\).

Hints

- Simplify the integrand before finding an antiderivative. - Use the binomial formula and the distributive property to expand the product. - When substituting the negative lower limit, check the signs of its powers carefully.

Solution

1. Expand the integrand: \((x-2)^2(x+1)=(x^2-4x+4)(x+1)=x^3-3x^2+4\). 2. An antiderivative is \(F(x)=\frac{1}{4}x^4-x^3+4x\). 3. Evaluate at the limits: \(F(1)=\frac{1}{4}-1+4=\frac{13}{4}\) and \(F(-2)=4+8-8=4\). 4. Therefore, \(F(1)-F(-2)=\frac{13}{4}-4=-\frac{3}{4}\).

Answer

\(-\frac{3}{4}\), or \(-0.75\)
Fundamental theorem of calculus 56
Let \(F(x)=\ln(x^2+4)\). First verify that \(F\) is an antiderivative of the integrand in \(\int_{0}^{2}\frac{2x}{x^2+4}\,\text{d}x\). Then evaluate the integral.

Hints

- Differentiate \(F\) to check whether it is an antiderivative. - Use the chain rule for the logarithm of a function. - Apply the Fundamental Theorem of Calculus at the two limits. - Use a logarithm property to simplify the difference.

Solution

1. Differentiate using the chain rule: \(F'(x)=\frac{1}{x^2+4}\cdot 2x=\frac{2x}{x^2+4}\). Therefore, \(F\) is an antiderivative of the integrand. 2. By the Fundamental Theorem of Calculus, \(\int_{0}^{2}\frac{2x}{x^2+4}\,\text{d}x=F(2)-F(0)\). 3. Evaluate: \(F(2)=\ln(8)\) and \(F(0)=\ln(4)\). 4. Thus, \(\ln(8)-\ln(4)=\ln\left(\frac{8}{4}\right)=\ln(2)\).

Answer

\(\ln(2)\)
Fundamental theorem of calculus 57
Differentiate to verify that \(F(x)=(2x-1)e^x\) is an antiderivative of \(f(x)=(2x+1)e^x\). Then evaluate \(\int_{0}^{1}(2x+1)e^x\,\text{d}x\).

Hints

- Use the product rule to differentiate \(F\). - To verify an antiderivative, show that its derivative equals the integrand. - Evaluate the antiderivative at the upper and lower limits. - Use parentheses when subtracting the lower-limit value.

Solution

1. Differentiate \(F\) using the product rule: \(F'(x)=2e^x+(2x-1)e^x\). 2. Combine like terms: \(F'(x)=e^x(2+2x-1)=(2x+1)e^x=f(x)\). Therefore, \(F\) is an antiderivative of \(f\). 3. Apply the Fundamental Theorem of Calculus: \(\int_{0}^{1}f(x)\,\text{d}x=F(1)-F(0)\). 4. Since \(F(1)=e\) and \(F(0)=-1\), the integral is \(e-(-1)=e+1\).

Answer

\(e+1\)
Fundamental theorem of calculus 58
Let \(f\) and \(g\) be continuous on \([a, b]\), with antiderivatives \(F\) and \(G\), respectively. Use the Fundamental Theorem of Calculus to prove the sum rule \(\int_a^b [f(x)+g(x)]\,\text{d}x=\int_a^b f(x)\,\text{d}x+\int_a^b g(x)\,\text{d}x\).

Hints

- Which function is an antiderivative of \(f+g\)? - Recall the derivative rule for a sum. - Apply the Fundamental Theorem of Calculus to each integral. - Rearrange the resulting terms so the two sides have the same form.

Solution

1. Since \((F+G)'=F'+G'=f+g\), the function \(F+G\) is an antiderivative of \(f+g\). 2. Apply the Fundamental Theorem of Calculus to the left side: \(\int_a^b [f(x)+g(x)]\,\text{d}x=[F(x)+G(x)]_a^b=F(b)+G(b)-F(a)-G(a)\). 3. Apply the theorem to the right side: \(\int_a^b f(x)\,\text{d}x+\int_a^b g(x)\,\text{d}x=[F(b)-F(a)]+[G(b)-G(a)]\). 4. Rearranging the right side gives \(F(b)+G(b)-F(a)-G(a)\), which is the same expression as the left side.

Answer

Because \(F+G\) is an antiderivative of \(f+g\), the left side equals \(F(b)+G(b)-F(a)-G(a)\). Evaluating the two integrals on the right gives \([F(b)-F(a)]+[G(b)-G(a)]\), which simplifies to the same expression.
Fundamental theorem of calculus 59
Simplify the integrand first, and then evaluate \(\int_{1}^{2}\left(\sqrt{3x}\sqrt{12x}-\frac{4}{x^3}\right)\,\text{d}x\).

Hints

- Combine the square roots into one radical. - Rewrite the fraction using a negative exponent. - Apply the power rule to each term. - Use the Fundamental Theorem of Calculus to evaluate the definite integral.

Solution

1. On \([1, 2]\), \(x>0\), so \(\sqrt{3x}\sqrt{12x}=\sqrt{36x^2}=6x\). Also, \(\frac{4}{x^3}=4x^{-3}\). Thus, the integrand is \(6x-4x^{-3}\). 2. An antiderivative is \(F(x)=3x^2+2x^{-2}=3x^2+\frac{2}{x^2}\). 3. Evaluate: \(F(2)=12+\frac{1}{2}=\frac{25}{2}\) and \(F(1)=3+2=5\). 4. Therefore, \(F(2)-F(1)=\frac{25}{2}-5=\frac{15}{2}=7.5\).

Answer

\(\frac{15}{2}\), or \(7.5\)
Fundamental theorem of calculus 60
Use exponent properties to simplify the integrand, and then evaluate \(\int_{0}^{1}\frac{e^{3x}+e^x}{e^{2x}}\,\text{d}x\).

Hints

- Split the numerator so that each term is divided by the denominator. - Use the quotient rule for exponents with the same base. - Check the derivative of \(e^{-x}\) when finding an antiderivative. - Recall the value of a nonzero base raised to the zero power.

Solution

1. Split the fraction and subtract exponents: \(\frac{e^{3x}}{e^{2x}}+\frac{e^x}{e^{2x}}=e^x+e^{-x}\). 2. An antiderivative is \(F(x)=e^x-e^{-x}\). 3. Evaluate at the limits: \(F(1)=e-e^{-1}=e-\frac{1}{e}\) and \(F(0)=1-1=0\). 4. Therefore, the integral equals \(e-\frac{1}{e}\).

Answer

\(e-\frac{1}{e}\)
Fundamental theorem of calculus 61
Let \(f(x)=\ln(x)+2\) for \(x>0\). a) Differentiate to verify that \(F(x)=x\ln(x)+x\) is an antiderivative of \(f\). b) Use \(F\) to evaluate \(\int_{1}^{e}f(x)\,\text{d}x\).

Hints

- Use the product rule to differentiate \(x\ln(x)\). - Recall the derivative of \(\ln(x)\). - Use the antiderivative to evaluate the definite integral. - Recall the values of \(\ln(e)\) and \(\ln(1)\).

Solution

1. For a), use the product rule: \(F'(x)=\ln(x)+x\cdot \frac{1}{x}+1=\ln(x)+2=f(x)\). Thus, \(F\) is an antiderivative of \(f\). 2. For b), apply the Fundamental Theorem of Calculus: \(\int_{1}^{e}f(x)\,\text{d}x=F(e)-F(1)\). 3. Since \(F(e)=e\ln(e)+e=2e\) and \(F(1)=\ln(1)+1=1\), the integral is \(2e-1\).

Answer

a) \(F'(x)=\ln(x)+2=f(x)\), so \(F\) is an antiderivative of \(f\). b) \(2e-1\)
Fundamental theorem of calculus 62
Let \(f(x)=\frac{\ln(x)}{x}\) for \(x>0\). a) Verify that \(F(x)=\frac{1}{2}(\ln(x))^2\) is an antiderivative of \(f\). b) Find the exact value of \(\int_{1}^{e^2}f(x)\,\text{d}x\).

Hints

- Apply the chain rule when differentiating the square of \(\ln(x)\). - Recall the derivative of \(\ln(x)\). - Simplify \(\ln(e^2)\) exactly. - Use the difference of the antiderivative values at the limits.

Solution

1. For a), differentiate using the chain rule: \(F'(x)=\frac{1}{2}\cdot 2\ln(x)\cdot \frac{1}{x}=\frac{\ln(x)}{x}=f(x)\). Therefore, \(F\) is an antiderivative of \(f\). 2. For b), \(\int_{1}^{e^2}f(x)\,\text{d}x=F(e^2)-F(1)\). 3. Evaluate: \(F(e^2)=\frac{1}{2}(\ln(e^2))^2=\frac{1}{2}\cdot 2^2=2\), and \(F(1)=0\). 4. The integral equals \(2\).

Answer

a) \(F'(x)=\frac{\ln(x)}{x}=f(x)\), so \(F\) is an antiderivative of \(f\). b) \(2\)
Fundamental theorem of calculus 63
Find the real value of \(a\) that satisfies \(\int_0^\pi a\sin(0.5x)\,\text{d}x=10\).

Hints

- Account for the inner factor when integrating the sine function. - Use the exact cosine values at \(0\) and \(\frac{\pi}{2}\). - Form a linear equation in \(a\). - Solve after evaluating the integral.

Solution

1. An antiderivative is \(F(x)=-2a\cos(0.5x)\). 2. Apply the bounds: \([-2a\cos(0.5x)]_0^\pi=-2a\cos\left(\frac{\pi}{2}\right)+2a\cos(0)=2a\). 3. Solve \(2a=10\), giving \(a=5\).

Answer

\(a=5\)
Fundamental theorem of calculus 64
Let \(f_k(x)=\frac{k}{x+2}\) for \(x\ge 0\). Find \(k\) so that \(\int_0^2 f_k(x)\,\text{d}x=\ln(16)\).

Hints

- Use the logarithmic antiderivative for \(\frac{1}{x+2}\). - Combine the difference of logarithms. - Rewrite \(16\) as a power of \(2\). - Compare the coefficients of \(\ln(2)\).

Solution

1. An antiderivative is \(F_k(x)=k\ln(x+2)\). 2. Apply the bounds: \(\int_0^2\frac{k}{x+2}\,\text{d}x=k(\ln(4)-\ln(2))=k\ln(2)\). 3. Since \(\ln(16)=\ln(2^4)=4\ln(2)\), \(k\ln(2)=4\ln(2)\), so \(k=4\).

Answer

\(k=4\)
Fundamental theorem of calculus 65
Find the positive integer \(a\) that satisfies \(\int_0^4\frac{8}{(x+a)^2}\,\text{d}x=1\).

Hints

- Rewrite the integrand using a negative exponent. - Apply the bounds to the antiderivative. - Clear the fractions in the resulting equation. - Use the condition that \(a\) is a positive integer.

Solution

1. An antiderivative is \(F(x)=-\frac{8}{x+a}\). 2. Apply the bounds: \(\frac{8}{a}-\frac{8}{a+4}=1\). 3. Combine the fractions: \(\frac{32}{a(a+4)}=1\), so \(a^2+4a-32=0\). 4. Factor: \((a-4)(a+8)=0\). The positive integer solution is \(a=4\).

Answer

\(a=4\)
Fundamental theorem of calculus 66
Let \(f(x)=\cos\left(\frac{\pi}{3}x\right)\). a) Give two consecutive zeros of \(f\). b) Evaluate \(\int_{0}^{3}f(x)\,\text{d}x\). Explain why this value is not the total area between the graph of \(f\) and the x-axis on \([0, 3]\).

Hints

- Recall where the cosine function equals zero. - Adapt the general cosine-zero formula to the argument in this function. - Reverse the chain rule when finding an antiderivative. - Determine where the graph is above and below the x-axis. - Distinguish between net signed area and total geometric area.

Solution

1. For a), solve \(\cos\left(\frac{\pi}{3}x\right)=0\). Since cosine is zero when its argument is \(\frac{\pi}{2}+k\pi\), \(\frac{\pi}{3}x=\frac{\pi}{2}+k\pi\), so \(x=\frac{3}{2}+3k\), where \(k\in\mathbb{Z}\). Two consecutive zeros are \(x=1.5\) and \(x=4.5\). 2. For b), an antiderivative is \(F(x)=\frac{3}{\pi}\sin\left(\frac{\pi}{3}x\right)\). Therefore, \(\int_{0}^{3}f(x)\,\text{d}x=\frac{3}{\pi}\left(\sin(\pi)-\sin(0)\right)=0\). 3. The graph is above the x-axis on \([0, 1.5]\) and below it on \([1.5, 3]\). The definite integral adds signed areas, so the equal positive and negative contributions cancel. Total geometric area would add their magnitudes instead.

Answer

a) Two consecutive zeros are, for example, \(x=1.5\) and \(x=4.5\). b) \(\int_{0}^{3}f(x)\,\text{d}x=0\). The graph lies both above and below the x-axis, so the definite integral gives net signed area rather than total geometric area.
Fundamental theorem of calculus 67
Let \(g(x)=e^{0.5x}-e\). a) Find the zero of \(g\). b) Evaluate \(\int_{0}^{4}g(x)\,\text{d}x\). Explain, in terms of net signed area, why this value is not the total area between the graph and the x-axis on \([0, 4]\).

Hints

- Solve the exponential equation by comparing exponents or taking logarithms. - Use the antiderivative rule for a function of the form \(e^{ax}\). - Determine the sign of the function on each side of its zero. - Recall how regions below the x-axis contribute to a definite integral.

Solution

1. For a), solve \(e^{0.5x}-e=0\). Then \(e^{0.5x}=e^1\), so \(0.5x=1\) and \(x=2\). 2. For b), an antiderivative is \(G(x)=2e^{0.5x}-ex\). Thus, \(\int_{0}^{4}g(x)\,\text{d}x=G(4)-G(0)=\left(2e^2-4e\right)-2=2e^2-4e-2\approx 1.90\). 3. The function is negative on \([0, 2)\) and positive on \((2, 4]\). The definite integral subtracts the area below the x-axis from the area above it. Total geometric area would require adding the absolute values of the two contributions.

Answer

a) The zero is \(x=2\). b) \(\int_{0}^{4}g(x)\,\text{d}x=2e^2-4e-2\approx 1.90\). This is net signed area, not total geometric area, because the function changes sign at \(x=2\).
Fundamental theorem of calculus 68
Define \(H(x)=\int_0^{x^2} e^{-t^2}\,\text{d}t\). 1. Find \(H(0)\). 2. Use the Fundamental Theorem of Calculus and the chain rule to find \(H'(x)\). 3. Determine where \(H\) is increasing and decreasing, and identify its absolute minimum.

Hints

- Equal integration limits give an integral of \(0\). - First apply the Fundamental Theorem at the upper limit \(x^2\). - Then multiply by the derivative of the upper-limit function. - The exponential factor is always positive, so use the remaining factor to determine the sign of the derivative.

Solution

1. When \(x=0\), the upper and lower limits are equal, so \(H(0)=\int_0^0 e^{-t^2}\,\text{d}t=0\). 2. Let \(u=x^2\). The Fundamental Theorem of Calculus gives the derivative with respect to the upper limit as \(e^{-u^2}\). Multiplying by \(u'=2x\) gives \(H'(x)=2xe^{-x^4}\). 3. Since \(e^{-x^4}>0\) for every real \(x\), the sign of \(H'(x)\) is the sign of \(x\). Thus, \(H\) decreases on \((-\infty, 0)\) and increases on \((0, \infty)\). Therefore, \(H\) has an absolute minimum at \(x=0\), with minimum value \(0\).

Answer

1. \(H(0)=0\) 2. \(H'(x)=2xe^{-x^4}\) 3. \(H\) decreases on \((-\infty, 0)\), increases on \((0, \infty)\), and has an absolute minimum of \(0\) at \(x=0\).
Fundamental theorem of calculus 69
Define \(Q(x)=\int_x^{2x}(t^2+1)\,\text{d}t\). 1. Use the Fundamental Theorem of Calculus and the chain rule to find \(Q'(x)\) without first evaluating the integral. 2. Find an explicit formula for \(Q(x)\), and differentiate it to verify your answer from part 1. 3. Find all zeros of \(Q\).

Hints

- Differentiate the upper-limit contribution and subtract the lower-limit contribution. - Multiply each integrand value by the derivative of its limit. - For the explicit formula, evaluate one antiderivative at \(2x\) and at \(x\). - Factor the formula before solving for its zeros.

Solution

1. Differentiate the contribution from each variable limit. The upper limit contributes \(((2x)^2+1)\cdot 2\), and the lower limit contributes \(-(x^2+1)\cdot 1\). Thus, \(Q'(x)=2(4x^2+1)-(x^2+1)=7x^2+1\). 2. An antiderivative of \(t^2+1\) is \(\frac{1}{3}t^3+t\). Therefore, \(Q(x)=\left[\frac{1}{3}t^3+t\right]_x^{2x}=\frac{8}{3}x^3+2x-\frac{1}{3}x^3-x=\frac{7}{3}x^3+x\). Differentiating gives \(Q'(x)=7x^2+1\), which matches part 1. 3. Factor: \(Q(x)=x\left(\frac{7}{3}x^2+1\right)\). The second factor is positive for every real \(x\), so the only zero is \(x=0\).

Answer

1. \(Q'(x)=7x^2+1\) 2. \(Q(x)=\frac{7}{3}x^3+x\) 3. The only zero is \(x=0\).
Fundamental theorem of calculus 70
Eero claims that \(\int_{-1}^{2}(x+1)(x-2)^2\,\text{d}x=0\) because the integrand is \(0\) at both endpoints. Explain why that reasoning is incorrect, and then use the Fundamental Theorem of Calculus to evaluate the integral.

Hints

- Distinguish values of the integrand from values of an antiderivative. - Simplify the integrand before integrating. - Apply the power rule term by term. - After finding an antiderivative, compare its endpoint values as required by the Fundamental Theorem.

Solution

1. The values of the integrand at the endpoints do not determine a definite integral. The integral depends on the accumulated values of the function throughout the interval. 2. Expand the integrand: \((x+1)(x-2)^2=(x+1)(x^2-4x+4)=x^3-3x^2+4\). 3. An antiderivative is \(F(x)=\frac14x^4-x^3+4x\). 4. Evaluate: \(F(2)=4-8+8=4\) and \(F(-1)=\frac14+1-4=-\frac{11}{4}\). Therefore, \(F(2)-F(-1)=4+\frac{11}{4}=\frac{27}{4}\).

Answer

The reasoning is incorrect because endpoint values of the integrand do not determine the accumulated integral. The integral equals \(\frac{27}{4}\).
Fundamental theorem of calculus 71
Find the real value of \(k\) that satisfies \(\int_0^\pi(k\sin(x)+x)\,\text{d}x=\frac{\pi^2}{2}+4\).

Hints

- Treat \(k\) as a constant while integrating. - Use the exact cosine values at \(0\) and \(\pi\). - Set the evaluated integral equal to the given expression. - Solve the resulting linear equation.

Solution

1. An antiderivative is \(F(x)=-k\cos(x)+\frac{x^2}{2}\). 2. Apply the bounds: \(F(\pi)-F(0)=2k+\frac{\pi^2}{2}\). 3. Set this equal to the given value: \(2k+\frac{\pi^2}{2}=\frac{\pi^2}{2}+4\). Thus, \(2k=4\) and \(k=2\).

Answer

\(k=2\)
Fundamental theorem of calculus 72
Let \(f(x)=x^4-2x^2\). 1. Find the first and second derivatives of \(f\). 2. Use the Fundamental Theorem of Calculus to find \(G(x)=\int_{1}^{x}f''(t)\,\text{d}t\). 3. Differentiate \(G\), compare the result with \(f''(x)\), and briefly explain how this illustrates that integration and differentiation are inverse processes.

Hints

- Apply the power rule for derivatives. - Recognize an antiderivative of the second derivative. - Use the Fundamental Theorem of Calculus at the limits \(1\) and \(x\). - Differentiate the result and compare it with the integrand.

Solution

1. The derivatives are \(f'(x)=4x^3-4x\) and \(f''(x)=12x^2-4\). 2. Since \(f'\) is an antiderivative of \(f''\), \(G(x)=f'(x)-f'(1)\). Because \(f'(1)=4-4=0\), \(G(x)=4x^3-4x\). 3. Differentiating gives \(G'(x)=12x^2-4=f''(x)\). Integrating a derivative recovers the original function up to a constant, and differentiating an accumulation function recovers its integrand.

Answer

1. \(f'(x)=4x^3-4x\); \(f''(x)=12x^2-4\) 2. \(G(x)=4x^3-4x\) 3. \(G'(x)=12x^2-4=f''(x)\)
Fundamental theorem of calculus 73
Let \(f(x)=k\sin(x)-1\), where \(k\) is real. Find \(k\) so that \(\int_0^\pi f(x)\,\text{d}x=0\).

Hints

- Treat \(k\) as a constant. - Be careful with the sign when integrating sine. - Use the cosine values at \(0\) and \(\pi\). - Set the evaluated integral equal to \(0\).

Solution

1. An antiderivative is \(F(x)=-k\cos(x)-x\). 2. Apply the bounds: \(F(\pi)-F(0)=2k-\pi\). 3. Set the integral equal to \(0\): \(2k-\pi=0\), so \(k=\frac{\pi}{2}\).

Answer

\(k=\frac{\pi}{2}\)
Fundamental theorem of calculus 74
Simplify the integrand, and then use an antiderivative to evaluate \(\int_{1}^{2}\frac{4x^4-3x^2+2}{2x^2}\,\text{d}x\).

Hints

- Simplify the rational expression before integrating. - Divide each term in the numerator by the denominator. - Rewrite the remaining reciprocal term with a negative exponent. - Use parentheses when subtracting the lower-limit value.

Solution

1. Divide each numerator term by \(2x^2\): \(\frac{4x^4-3x^2+2}{2x^2}=2x^2-\frac{3}{2}+x^{-2}\). 2. An antiderivative is \(F(x)=\frac{2}{3}x^3-\frac{3}{2}x-x^{-1}\). 3. Evaluate: \(F(2)=\frac{16}{3}-3-\frac{1}{2}=\frac{11}{6}\), and \(F(1)=\frac{2}{3}-\frac{3}{2}-1=-\frac{11}{6}\). 4. Therefore, \(F(2)-F(1)=\frac{11}{6}+\frac{11}{6}=\frac{11}{3}\).

Answer

\(\frac{11}{3}\), or \(3\frac{2}{3}\)
Fundamental theorem of calculus 75
Evaluate \(\int_{0}^{2}\frac{x^2+2x+5}{x^2+2x+1}\,\text{d}x\).

Hints

- Compare the numerator and denominator. - Rewrite the denominator as a perfect square. - Split the rational expression into simpler terms. - Express \(\frac{k}{(x+a)^2}\) using a negative exponent before integrating.

Solution

1. Recognize that \(x^2+2x+1=(x+1)^2\), and rewrite the numerator as \(x^2+2x+5=(x+1)^2+4\). 2. Then the integrand becomes \(1+\frac{4}{(x+1)^2}=1+4(x+1)^{-2}\). 3. An antiderivative is \(F(x)=x-\frac{4}{x+1}\). 4. Evaluate: \(F(2)=2-\frac{4}{3}=\frac{2}{3}\), and \(F(0)=-4\). 5. Therefore, \(F(2)-F(0)=\frac{2}{3}+4=\frac{14}{3}\).

Answer

\(\frac{14}{3}\)
Fundamental theorem of calculus 76
Evaluate \(\int_{-1}^{2}(x^2-1)(x+2)\,\text{d}x\).

Hints

- Expand the product into a polynomial before integrating. - Apply the power rule term by term. - Check signs carefully when substituting a negative lower limit. - Use the Fundamental Theorem of Calculus.

Solution

1. Expand the integrand: \((x^2-1)(x+2)=x^3+2x^2-x-2\). 2. An antiderivative is \(F(x)=\frac{1}{4}x^4+\frac{2}{3}x^3-\frac{1}{2}x^2-2x\). 3. Evaluate: \(F(2)=\frac{10}{3}\), and \(F(-1)=\frac{13}{12}\). 4. Therefore, \(F(2)-F(-1)=\frac{40}{12}-\frac{13}{12}=\frac{9}{4}\).

Answer

\(\frac{9}{4}\), or \(2.25\)
Fundamental theorem of calculus 77
Let \(n\) be a positive integer and \(k>1\). Derive a formula for \(\int_1^k\sqrt[n]{x}\,\text{d}x\) in terms of \(k\) and \(n\).

Hints

- Rewrite the radical as a rational exponent. - Apply the power rule symbolically. - Remember that \(1\) raised to any real power is \(1\). - Use upper bound minus lower bound.

Solution

1. Rewrite the integrand: \(\sqrt[n]{x}=x^{1/n}\). 2. By the power rule, an antiderivative is \(F(x)=\frac{x^{1+1/n}}{1+1/n}=\frac{n}{n+1}x^{(n+1)/n}\). 3. Apply the bounds: \(\int_1^k\sqrt[n]{x}\,\text{d}x=\frac{n}{n+1}\left(k^{(n+1)/n}-1\right)\).

Answer

\(\int_1^k\sqrt[n]{x}\,\text{d}x=\frac{n}{n+1}\left(k^{(n+1)/n}-1\right)\)
Fundamental theorem of calculus 78
Evaluate \(\int_{-1}^{2}f(x)\,\text{d}x\) for the piecewise-defined function \(f(x)=\begin{cases}e^{2x},&x\le 0\\1-x,&x>0.\end{cases}\)

Hints

- Split the interval where the function definition changes. - Evaluate each piece using its own antiderivative. - Add the two definite integrals.

Solution

1. Split the integral where the formula changes: \(\int_{-1}^{0}e^{2x}\,\text{d}x+\int_0^2(1-x)\,\text{d}x\). 2. The first part is \([\frac{1}{2}e^{2x}]_{-1}^{0}=\frac{1}{2}-\frac{1}{2e^2}\). 3. The second part is \([x-\frac{1}{2}x^2]_0^2=0\). 4. Therefore, the total is \(\frac{1}{2}-\frac{1}{2e^2}\approx 0.432\).

Answer

\(\frac{1}{2}-\frac{1}{2e^2}\approx 0.432\)
Fundamental theorem of calculus 79
Let \(f(x)=x^2-a\). Find the real value of \(a\) so that \(\int_1^3f(x)\,\text{d}x=\frac{2}{3}\).

Hints

- Treat \(a\) as a constant while integrating. - Apply upper bound minus lower bound. - Form an equation in \(a\). - Solve the linear equation.

Solution

1. An antiderivative is \(F(x)=\frac{x^3}{3}-ax\). 2. Apply the bounds: \(F(3)-F(1)=\left(9-3a\right)-\left(\frac{1}{3}-a\right)=\frac{26}{3}-2a\). 3. Set this equal to \(\frac{2}{3}\): \(\frac{26}{3}-2a=\frac{2}{3}\), so \(2a=8\) and \(a=4\).

Answer

\(a=4\)
Fundamental theorem of calculus 80
Let \(f(x)=\frac{2}{x}\). a) Evaluate \(I_1=\int_{1}^{e^2}f(x)\,\text{d}x\). b) Evaluate \(I_2=\int_{-e}^{-1}f(x)\,\text{d}x\). c) Use the symmetry and position of the graph of \(f\) to explain why \(I_1\) is positive and \(I_2\) is negative.

Hints

- Recall the antiderivative of the reciprocal function. - Use absolute value inside the logarithm for negative limits. - Simplify logarithms of powers of \(e\). - Relate the sign of a definite integral to whether the graph lies above or below the x-axis.

Solution

1. An antiderivative on either interval is \(F(x)=2\ln|x|\). 2. For a), \(I_1=2\ln(e^2)-2\ln(1)=4\). 3. For b), \(I_2=2\ln|-1|-2\ln|-e|=0-2=-2\). 4. The function is odd because \(f(-x)=-f(x)\). Its graph lies above the x-axis for \(x>0\) and below the x-axis for \(x<0\). Therefore, the signed area in part a) is positive, while the signed area in part b) is negative.

Answer

a) \(I_1=4\) b) \(I_2=-2\) c) The graph is symmetric about the origin. It is above the x-axis on the interval for \(I_1\) and below the x-axis on the interval for \(I_2\), so the integrals have opposite signs.
Fundamental theorem of calculus 81
Find the exact value of \(\int_{2}^{4}\frac{x-2}{x^2}\,\text{d}x\).

Hints

- Split the fraction into simpler terms. - Recall which function has derivative \(\frac{1}{x}\). - Rewrite the second term with a negative exponent. - Use logarithm properties to combine the final expression.

Solution

1. Split and simplify the integrand: \(\frac{x-2}{x^2}=\frac{1}{x}-2x^{-2}\). 2. An antiderivative is \(F(x)=\ln(x)+\frac{2}{x}\) on \([2, 4]\). 3. Evaluate: \(F(4)=\ln(4)+\frac{1}{2}\), and \(F(2)=\ln(2)+1\). 4. Therefore, \(F(4)-F(2)=\ln(4)-\ln(2)-\frac{1}{2}=\ln(2)-\frac{1}{2}\).

Answer

\(\ln(2)-\frac{1}{2}\)
Fundamental theorem of calculus 82
Simplify the rational expression by division or by rewriting the numerator, and then evaluate \(\int_{0}^{1}\frac{2x+3}{x+2}\,\text{d}x\).

Hints

- Rewrite the numerator so it contains a multiple of the denominator. - Split the expression into a constant and a simple reciprocal term. - Recall the antiderivative of \(\frac{1}{x+k}\). - Use parentheses when subtracting the lower-limit value.

Solution

1. Rewrite the numerator: \(2x+3=2(x+2)-1\). Therefore, \(\frac{2x+3}{x+2}=2-\frac{1}{x+2}\). 2. An antiderivative is \(F(x)=2x-\ln(x+2)\) on \([0, 1]\). 3. Evaluate: \(F(1)=2-\ln(3)\), and \(F(0)=-\ln(2)\). 4. Thus, \(F(1)-F(0)=2-\ln(3)+\ln(2)=2+\ln\left(\frac{2}{3}\right)\).

Answer

\(2+\ln\left(\frac{2}{3}\right)\)
Fundamental theorem of calculus 83
Find the exact value of \(\int_{0}^{1}(e^x+e^{-x})^2\,\text{d}x\).

Hints

- Expand the squared binomial before integrating. - Use exponent properties to simplify \(e^xe^{-x}\). - Find an antiderivative of each resulting term. - Evaluate carefully at \(x=0\), where exponential terms equal \(1\).

Solution

1. Expand the square: \((e^x+e^{-x})^2=e^{2x}+2e^xe^{-x}+e^{-2x}=e^{2x}+2+e^{-2x}\). 2. An antiderivative is \(F(x)=\frac{1}{2}e^{2x}+2x-\frac{1}{2}e^{-2x}\). 3. Evaluate: \(F(1)=\frac{1}{2}e^2+2-\frac{1}{2}e^{-2}\), and \(F(0)=\frac{1}{2}-\frac{1}{2}=0\). 4. Therefore, the integral is \(\frac{1}{2}e^2+2-\frac{1}{2}e^{-2}\).

Answer

\(\frac{1}{2}e^2+2-\frac{1}{2}e^{-2}\)
Fundamental theorem of calculus 84
Mika differentiates the accumulation function \(H(x)=\int_1^{3x-2}(t^2+1)\,\text{d}t\) and writes \(H'(x)=(3x-2)^2+1\). a) Explain Mika's error and find the correct expression for \(H'(x)\). b) Find \(H(1)\) and \(H'(1)\). c) Explain why \(H\) is strictly increasing and why \(x=1\) is its only zero.

Hints

- Apply the Fundamental Theorem of Calculus and then the chain rule to the upper limit. - An integral with identical lower and upper limits equals zero. - Check the sign of \((3x-2)^2+1\) for all real \(x\). - A strictly increasing function can cross the x-axis at most once.

Solution

1. The upper limit is the composite function \(3x-2\), so the chain rule contributes its derivative, \(3\). Therefore, \(H'(x)=3[(3x-2)^2+1]\). 2. When \(x=1\), the upper limit is \(1\), so \(H(1)=\int_1^1(t^2+1)\,\text{d}t=0\). Also, \(H'(1)=3(1^2+1)=6\). 3. Because \((3x-2)^2+1>0\) for every real \(x\), \(H'(x)>0\) for every real \(x\). Thus, \(H\) is strictly increasing. Since \(H(1)=0\), a strictly increasing function cannot have another zero.

Answer

a) The missing factor is the derivative of the upper limit: \(H'(x)=3[(3x-2)^2+1]\). b) \(H(1)=0\) and \(H'(1)=6\) c) \(H'(x)>0\) for every \(x\), so \(H\) is strictly increasing and \(x=1\) is its only zero.
Fundamental theorem of calculus 85
Panel a) shows the graph of a function \(f\). Panel b) shows three curves labeled g, h, and k. Exactly one curve is an antiderivative \(F\) of \(f\). a) Identify the curve that can represent \(F\). Justify your choice from the zeros and sign of \(f\). b) Using only the graph of the curve you identified, read \(F(0)\) and \(F(2)\), then use the Fundamental Theorem of Calculus to find \(\int_0^2 f(x)\,\text{d}x\).
Figure for problem 532444

Hints

- Zeros of \(f\) correspond to horizontal tangents of an antiderivative. - Use the sign of \(f\) to decide where an antiderivative must increase or decrease. - After choosing the curve, read its endpoint values from the coordinate grid. - The definite integral is the change in the antiderivative between the two endpoints.

Solution

1. Because \(F'=f\), the zeros of \(f\) at \(x=0\) and \(x=2\) must be critical points of \(F\). 2. The graph of \(f\) is positive for \(x<0\), negative for \(0<x<2\), and positive for \(x>2\). Thus \(F\) must increase, then decrease, then increase. 3. Only curve g has a local maximum at \(x=0\) and a local minimum at \(x=2\), so g is the possible antiderivative. 4. From curve g, \(F(0)=1\) and \(F(2)=0\). 5. By the Fundamental Theorem of Calculus, \(\int_0^2 f(x)\,\text{d}x=F(2)-F(0)=0-1=-1\).

Answer

a) Curve g b) \(F(0)=1\), \(F(2)=0\), and \(\int_0^2 f(x)\,\text{d}x=-1\).
Fundamental theorem of calculus 86
The graph of a function \(f\) is shown. a) An antiderivative \(F\) of \(f\) has a local maximum at some x-value. Use the graph to find that x-value and justify your answer. b) A particular antiderivative \(F_1\) satisfies \(F_1(0)=3\). The signed area between the graph of \(f\) and the x-axis on \([-2, 0]\) is \(4\). Use this signed area to find \(F_1(-2)\).
Figure for problem 532610

Hints

- A local maximum occurs when the derivative changes from positive to negative. - Use the graph of \(f\) to locate that sign change. - Relate the given signed area to \(F_1(0)-F_1(-2)\). - Use the known value \(F_1(0)=3\).

Solution

1. A local maximum of \(F\) occurs where \(f=F'\) changes from positive to negative. The graph shows this sign change at \(x=1\). 2. By the Fundamental Theorem of Calculus, \(\int_{-2}^{0}f(x)\,\text{d}x=F_1(0)-F_1(-2)\). 3. The signed area on \([-2, 0]\) is \(4\). Therefore, \(4=3-F_1(-2)\). 4. Solving gives \(F_1(-2)=-1\).

Answer

a) \(x=1\) b) \(F_1(-2)=-1\)
Fundamental theorem of calculus 87
Let \(f\) be positive and continuous for all real numbers. Part of its graph is shown. Define \(H(x)=\int_0^{2x}f(t)\,\text{d}t\). a) Find \(H'(x)\) in terms of \(f\). b) Use the graph to find \(H'(0)\) and \(H'(1)\). c) Explain why \(H\) is strictly increasing on \(\mathbb{R}\).
Figure for problem 532749

Hints

- Apply the Fundamental Theorem of Calculus to the variable upper limit. - Include the derivative of \(2x\) from the chain rule. - Read \(f(0)\) and \(f(2)\) from the graph. - Use the stated positivity of \(f\), not just the visible part of its graph, to explain the result for all real numbers.

Solution

1. The Fundamental Theorem of Calculus gives the integrand evaluated at the upper limit, and the chain rule contributes the derivative of \(2x\). Thus, \(H'(x)=2f(2x)\). 2. From the graph, \(f(0)=1\), so \(H'(0)=2f(0)=2\). Also, \(f(2)=5\), so \(H'(1)=2f(2)=10\). 3. The problem states that \(f\) is positive for every real input. Therefore, \(H'(x)=2f(2x)>0\) for every real \(x\), so \(H\) is strictly increasing on \(\mathbb{R}\).

Answer

a) \(H'(x)=2f(2x)\) b) \(H'(0)=2\) and \(H'(1)=10\) c) Since \(f(2x)>0\) for every real \(x\) by the given assumption, \(H'(x)>0\); hence \(H\) is strictly increasing.
Fundamental theorem of calculus 88
The graph of \(f'\) is shown for \(0\le x\le6\), and \(f(0)=0\). a) Where does \(f\) have an inflection point? Explain using the graph of \(f'\). b) Use area to find \(f(3)\). c) Describe where \(f\) increases, decreases, is concave up, and is concave down. Give the coordinates of its inflection point and its maximum.
Figure for problem 534281

Hints

- What does the slope of the derivative graph tell you about the concavity of the original function? - Areas under the derivative graph give changes in the original function. - Use the derivative's sign to locate a maximum; use its direction of change to locate an inflection point.

Solution

1. The derivative increases until \(x=1\) and decreases afterward. Therefore \(f\) changes from concave up to concave down at \(x=1\). 2. The region under \(f'\) from \(0\) to \(3\) is a triangle with base \(3\) and height \(2\). Thus \(f(3)=f(0)+\frac{1}{2}\cdot3\cdot2=3\). 3. The area from \(0\) to \(1\) is \(1\), so the inflection point is \((1,1)\). Since \(f'>0\) for \(0<x<3\) and \(f'<0\) for \(3<x<6\), \(f\) increases, then decreases, with an absolute maximum at \((3,3)\). It is concave up on \((0,1)\) and concave down on \((1,6)\).

Answer

a) \(x=1\), where \(f'\) changes from increasing to decreasing. b) \(f(3)=3\) c) Increasing on \((0,3)\), decreasing on \((3,6)\); concave up on \((0,1)\), concave down on \((1,6)\). Inflection point: \((1,1)\). Absolute maximum: \((3,3)\).
Fundamental theorem of calculus 89
The graph of an antiderivative \(F\) of \(f\) is shown. a) Use the graph to evaluate \(\int_{0}^{3}f(x)\,\text{d}x\). b) On which intervals in \((0, 3)\) is \(f\) negative, and on which interval is it positive? c) Explain how the integral in part a) can equal \(0\) even though \(f\) is not the zero function.
Figure for problem 534665

Hints

- Use \(\int_a^b f(x)\,\text{d}x=F(b)-F(a)\). - The sign of \(F'\) is determined by whether \(F\) is increasing or decreasing. - A zero definite integral represents zero net change, not necessarily a zero integrand.

Solution

1. By the Fundamental Theorem of Calculus, \(\int_{0}^{3}f(x)\,\text{d}x=F(3)-F(0)\). The graph shows \(F(3)=4\) and \(F(0)=4\), so the integral is \(0\). 2. Since \(f=F'\), \(f\) is negative where \(F\) decreases and positive where \(F\) increases. The graph decreases on \((0, 2)\) and increases on \((2, 3)\). Therefore, \(f<0\) on \((0, 2)\) and \(f>0\) on \((2, 3)\). 3. The decrease in \(F\) from \(x=0\) to \(x=2\) is exactly balanced by its increase from \(x=2\) to \(x=3\). Equivalently, the negative and positive signed contributions of \(f\) cancel.

Answer

a) \(0\) b) \(f<0\) on \((0, 2)\), and \(f>0\) on \((2, 3)\). c) The negative and positive signed contributions cancel, so the net integral is \(0\).
Fundamental theorem of calculus 90
The graphs of a function \(f\) and one of its antiderivatives \(g\) are shown. Evaluate \(\int_{-2}^{2}f(x)\,\text{d}x\) in two ways: a) using endpoint values of \(g\); b) using symmetry of \(f\).
Figure for problem 534667

Hints

- For the first method, read \(g(-2)\) and \(g(2)\) from the graph. - For the second method, compare the portions of the graph of \(f\) on opposite sides of the origin. - At matching x-values on opposite sides of the origin, how do the heights of \(f\) compare?

Solution

1. By the Fundamental Theorem of Calculus, \(\int_{-2}^{2}f(x)\,\text{d}x=g(2)-g(-2)\). The graph shows \(g(2)=0\) and \(g(-2)=0\), so the integral is \(0\). 2. The graph of \(f\) has origin symmetry, so \(f\) is odd. The signed areas on \([-2, 0]\) and \([0, 2]\) have equal magnitudes and opposite signs. Therefore, the integral is also \(0\) by symmetry.

Answer

a) \(g(2)-g(-2)=0-0=0\) b) Since \(f\) is odd and the interval is symmetric about \(0\), the integral is \(0\).
Fundamental theorem of calculus 91
A smooth curve is given by \(y=f(t)\), where \(f'\) is continuous for \(t>0\). For \(x>1\), let \(S(x)=\int_1^{x^2}\sqrt{1+[f'(t)]^2}\,\text{d}t\) be the curve's length from \(t=1\) to \(t=x^2\). Find \(S'(x)\) and explain the factor that comes from moving the endpoint.

Hints

- View the expression as an accumulation with a moving endpoint. - The endpoint is itself a function of \(x\). - Account for both the value of the length density and the rate at which the endpoint moves.

Solution

1. The integrand evaluated at the upper limit is \(\sqrt{1+[f'(x^2)]^2}\). 2. The upper limit \(x^2\) has derivative \(2x\). 3. By the Fundamental Theorem of Calculus and the chain rule, \(S'(x)=2x\sqrt{1+[f'(x^2)]^2}\). The factor \(2x\) accounts for how quickly the horizontal endpoint \(x^2\) moves.

Answer

\(S'(x)=2x\sqrt{1+[f'(x^2)]^2}\). The factor \(2x\) is the rate at which the upper endpoint moves.
Fundamental theorem of calculus 92
Let \(h\) be twice continuously differentiable, and define \(I(x)=\int_{a}^{x}h'(t)\,\text{d}t\). 1. Use the Fundamental Theorem of Calculus to write \(I(x)\) without an integral sign. 2. Find the derivative of \(I\), and justify your result. 3. Use parts 1 and 2 to illustrate both meanings of the statement “integration is the inverse of differentiation”: a) Integrating a derivative recovers the original function up to a constant. b) Differentiating an accumulation function recovers the original integrand.

Hints

- Apply the Fundamental Theorem of Calculus in general form. - Identify an antiderivative of \(h'\). - Treat \(a\) and \(h(a)\) as constants. - Compare the roles of antiderivatives and derivatives.

Solution

1. Since \(h\) is an antiderivative of \(h'\), \(I(x)=h(x)-h(a)\). 2. Because \(h(a)\) is constant with respect to \(x\), \(\frac{dI}{dx}=h'(x)\). 3. For a), integrating \(h'\) gives \(h(x)\) plus the constant \(-h(a)\). For b), differentiating the accumulation function gives its integrand \(h'(x)\).

Answer

1. \(I(x)=h(x)-h(a)\) 2. \(\frac{dI}{dx}=h'(x)\) 3. a) Integrating \(h'\) recovers \(h\) up to a constant. b) Differentiating \(I\) recovers its integrand \(h'\).

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