Aimathic
Login | English | Deutsch

Free math worksheets

Build your own math worksheets from 30,000+ problems for grades 3 to 12, from fractions to AP Calculus. Every problem comes with step-by-step solutions.

Integration by parts

Click problems to add them to your worksheet.

52507312
Find one antiderivative \(F\) of \(f(x)=(x+1)e^{3x}\).

Hints

- Use integration by parts for the product of a linear function and an exponential function. - Differentiate the linear factor and integrate the exponential factor. - Account for the inner derivative in \(e^{3x}\). - Factor out the exponential term when simplifying.

Solution

1. Use integration by parts with \(u=x+1\) and \(dv=e^{3x}\,dx\). Then \(du=dx\) and \(v=\frac{1}{3}e^{3x}\). 2. Therefore, \(\int(x+1)e^{3x}\,dx=\frac{1}{3}(x+1)e^{3x}-\frac{1}{3}\int e^{3x}\,dx\). 3. Evaluate the remaining integral: \(\frac{1}{3}(x+1)e^{3x}-\frac{1}{9}e^{3x}\). 4. Simplify to obtain \(F(x)=\left(\frac{x}{3}+\frac{2}{9}\right)e^{3x}\).

Answer

\(F(x)=\left(\frac{x}{3}+\frac{2}{9}\right)e^{3x}\)
52507412
Find one antiderivative \(F\) of \(f(x)=4x\cos(2x)\).

Hints

- Choose the factor that becomes simpler when differentiated. - Account for the inner derivative when integrating \(\cos(2x)\). - Track the sign when integrating sine. - Differentiate your result to verify it.

Solution

1. Use integration by parts with \(u=4x\) and \(dv=\cos(2x)\,dx\). Then \(du=4\,dx\) and \(v=\frac{1}{2}\sin(2x)\). 2. Apply the formula: \(\int 4x\cos(2x)\,dx=2x\sin(2x)-2\int\sin(2x)\,dx\). 3. Since \(\int 2\sin(2x)\,dx=-\cos(2x)\), the result is \(F(x)=2x\sin(2x)+\cos(2x)\).

Answer

\(F(x)=2x\sin(2x)+\cos(2x)\)
53020112
Find one antiderivative \(F\) of \(f(x)=(2-x)\sin(2x)\).

Hints

- Differentiate the linear factor. - Use integration by parts. - Account for the inner factor when integrating \(\sin(2x)\) and \(\cos(2x)\). - Track the signs carefully.

Solution

1. Use integration by parts with \(u=2-x\) and \(dv=\sin(2x)\,dx\). Then \(du=-dx\) and \(v=-\frac{1}{2}\cos(2x)\). 2. Therefore, \(F(x)=-\frac{1}{2}(2-x)\cos(2x)-\frac{1}{2}\int\cos(2x)\,dx\). 3. Since \(\int\cos(2x)\,dx=\frac{1}{2}\sin(2x)\), \(F(x)=\left(\frac{x}{2}-1\right)\cos(2x)-\frac{1}{4}\sin(2x)\).

Answer

\(F(x)=\left(\frac{x}{2}-1\right)\cos(2x)-\frac{1}{4}\sin(2x)\)
54914712
Evaluate \(\int x^3\ln(x)\,\text{d}x\) for \(x>0\). Explain why the logarithmic factor should be differentiated rather than integrated.

Hints

- Choose the factor whose derivative becomes simpler. - Choose the other factor so its antiderivative is immediate. - After applying integration by parts, simplify the remaining power integral.

Solution

1. Choose \(u=\ln(x)\) and \(\text{d}v=x^3\,\text{d}x\), so \(\text{d}u=\frac{1}{x}\,\text{d}x\) and \(v=\frac{x^4}{4}\). 2. Integration by parts gives \(\frac{x^4}{4}\ln(x)-\frac{1}{4}\int x^3\,\text{d}x\). 3. The result is \(\frac{x^4}{4}\ln(x)-\frac{x^4}{16}+C\). 4. Differentiating \(\ln(x)\) simplifies it to \(1/x\), while attempting to integrate it would not simplify the product.

Answer

\(\frac{x^4}{4}\ln(x)-\frac{x^4}{16}+C\)
54915012
Evaluate \(\int x\sin(x)\,\text{d}x\) using integration by parts. Verify the result by differentiation.

Hints

- Differentiate the algebraic factor and integrate the trigonometric factor. - Track the negative sign in the antiderivative of \(\sin(x)\). - Verify the final expression with the product rule.

Solution

1. Let \(u=x\) and \(\text{d}v=\sin(x)\,\text{d}x\), so \(\text{d}u=\text{d}x\) and \(v=-\cos(x)\). 2. Integration by parts gives \(-x\cos(x)+\int\cos(x)\,\text{d}x\). 3. Therefore, the antiderivative is \(-x\cos(x)+\sin(x)+C\). 4. Differentiation gives \(-\cos(x)+x\sin(x)+\cos(x)=x\sin(x)\).

Answer

\(-x\cos(x)+\sin(x)+C\)
54915412
Use integration by parts to evaluate exactly: \(\int_0^1 xe^{-x}\,\text{d}x\).

Hints

- Differentiate the algebraic factor and integrate the exponential factor. - Track the negative sign in an antiderivative of \(e^{-x}\). - Apply the bounds to both terms before combining them.

Solution

1. Let \(u=x\) and \(\text{d}v=e^{-x}\,\text{d}x\). Then \(\text{d}u=\text{d}x\) and \(v=-e^{-x}\). 2. Integration by parts gives \(\int_0^1xe^{-x}\,\text{d}x=[-xe^{-x}]_0^1+\int_0^1e^{-x}\,\text{d}x\). 3. Evaluate: \(-\frac{1}{e}+[-e^{-x}]_0^1=-\frac{1}{e}+1-\frac{1}{e}=1-\frac{2}{e}\).

Answer

\(1-\frac{2}{e}\)
54915712
A student writes \(\int\ln(2x)\,\text{d}x=x\ln(2x)+C\) for \(x>0\). Identify the error and give the correct antiderivative.

Hints

- Check the proposed result by differentiation before trying to repair it. - Think of the integrand as the product of a function and \(1\). - What term would cancel the extra derivative?

Solution

1. Differentiating the student's expression gives \(\ln(2x)+1\), so it has an extra constant term. 2. Treat \(\ln(2x)\) as a product with \(1\). The transformed integral is \(x\ln(2x)-\int 1\,\text{d}x\). 3. The correct antiderivative is \(x\ln(2x)-x+C\).

Answer

The student's expression differentiates to \(\ln(2x)+1\), not \(\ln(2x)\). The correct antiderivative is \(x\ln(2x)-x+C\).
55016512
For each integral, choose \(u\) and \(dv\) for integration by parts. Do not evaluate the integrals. a) \(\int xe^x\,dx\) b) \(\int x^2\cos(x)\,dx\) c) \(\int\ln(x)\,dx\), for \(x>0\)

Hints

- Prefer to differentiate a factor that becomes simpler. - Choose \(dv\) so its antiderivative is immediate. - A single logarithmic function can be treated as a product with \(1\).

Solution

1. a) Choose \(u=x\) and \(dv=e^x\,dx\). Differentiating \(x\) simplifies it, while \(e^x\) is easy to integrate. 2. b) Choose \(u=x^2\) and \(dv=\cos(x)\,dx\). Differentiating the polynomial lowers its degree. 3. c) View the integrand as \(\ln(x)\cdot1\). Choose \(u=\ln(x)\) and \(dv=dx\), because differentiating the logarithm produces \(1/x\).

Answer

a) \(u=x\), \(dv=e^x\,dx\) b) \(u=x^2\), \(dv=\cos(x)\,dx\) c) \(u=\ln(x)\), \(dv=dx\)
52505612
Evaluate the integral using integration by parts: \(\int_{0}^{\frac{\pi}{2}}(2x-1)\sin(x) \, dx\).

Hints

- Choose the factor that becomes simpler when differentiated. - Track the negative sign when integrating sine. - Recall the sine and cosine values at \(0\) and \(\frac{\pi}{2}\). - Evaluate the complete integration-by-parts expression at both limits.

Solution

1. Choose \(u=2x-1\) and \(dv=\sin(x)\,dx\). Then \(du=2\,dx\) and \(v=-\cos(x)\). 2. Apply integration by parts: \(\int_0^{\frac{\pi}{2}}(2x-1)\sin(x)\,dx=[-(2x-1)\cos(x)]_0^{\frac{\pi}{2}}+2\int_0^{\frac{\pi}{2}}\cos(x)\,dx\). 3. Combine the terms: \([-(2x-1)\cos(x)+2\sin(x)]_0^{\frac{\pi}{2}}\). 4. Substitute the limits. The upper value is \(2\), and the lower value is \(1\), so the integral equals \(1\).

Answer

\(1\)
52506312
Complete the exponent in \(\int_{0}^{1}xe^{\square} \, dx\) in two different ways so that each resulting integral can be evaluated by a familiar method. Use integration by parts for one choice and substitution for the other. Evaluate both integrals.

Hints

- Choose one exponent whose exponential factor remains simple under differentiation. - For substitution, look for an exponent whose derivative is a constant multiple of \(x\). - Integration by parts is useful when differentiating one factor simplifies it. - Check that each chosen exponent leads to the method requested.

Solution

1. Choose the exponent \(x\). Then \(\int_0^1xe^x\,dx\) is evaluated by integration by parts. With \(u=x\) and \(dv=e^x\,dx\), an antiderivative is \((x-1)e^x\). Thus \([(x-1)e^x]_0^1=1\). 2. Choose the exponent \(x^2\). Then \(\int_0^1xe^{x^2}\,dx\) is evaluated by substitution. Let \(u=x^2\), so \(du=2x\,dx\). Therefore, \(\int_0^1xe^{x^2}\,dx=\frac{1}{2}\int_0^1e^u\,du=\frac{e-1}{2}\).

Answer

One valid pair is: Exponent \(x\): integration by parts gives \(1\). Exponent \(x^2\): substitution gives \(\frac{e-1}{2}\).
52507112
Let \(f(x)=\ln(5x)\) for \(x>0\). Use integration by parts to evaluate the accumulation function \(I_{0.2}(x)=\int_{0.2}^{x}\ln(5t) \, dt\), and thereby obtain an antiderivative of \(f\).

Hints

- Write the integrand as a product with \(1\). - Differentiate the logarithmic factor and integrate the constant factor. - Simplify the remaining integral after applying integration by parts. - Use \(\ln(1)=0\) at the lower limit.

Solution

1. Use integration by parts with \(u=\ln(5t)\) and \(dv=dt\). Then \(du=\frac{1}{t}\,dt\) and \(v=t\). 2. Thus \(\int\ln(5t)\,dt=t\ln(5t)-\int 1\,dt=t\ln(5t)-t\). 3. Evaluate the accumulation function: \(I_{0.2}(x)=[t\ln(5t)-t]_{0.2}^{x}\). 4. Since \(\ln(5\cdot 0.2)=\ln(1)=0\), \(I_{0.2}(x)=x\ln(5x)-x+0.2\).

Answer

\(I_{0.2}(x)=x\ln(5x)-x+0.2\)
52508312
Evaluate \(\int_{1}^{e}\frac{\ln(x)}{x} \, dx\). Use integration by parts so that the original integral appears again, then solve the resulting equation.

Hints

- Split the integrand into two factors that are both related to \(\ln(x)\). - Choose a factor whose antiderivative matches the other factor. - Identify the repeated integral after applying integration by parts. - Treat the integral as an unknown in an algebraic equation.

Solution

1. Let \(I=\int_1^e\frac{\ln(x)}{x}\,dx\). Choose \(u=\ln(x)\) and \(dv=\frac{1}{x}\,dx\). Then \(du=\frac{1}{x}\,dx\) and \(v=\ln(x)\). 2. Integration by parts gives \(I=[\ln^2(x)]_1^e-I\). 3. Therefore, \(2I=[\ln^2(x)]_1^e=\ln^2(e)-\ln^2(1)=1\). 4. Hence \(I=\frac{1}{2}\).

Answer

\(\frac{1}{2}\)
52508912
Evaluate \(\int_{0}^{1}x^2e^{2x} \, dx\) by applying integration by parts twice.

Hints

- Differentiate the polynomial factor so its degree decreases. - Use integration by parts on the remaining product again. - Account for the factor \(2\) when integrating \(e^{2x}\). - Evaluate the complete antiderivative at the limits.

Solution

1. Choose \(u=x^2\) and \(dv=e^{2x}\,dx\). Then \(du=2x\,dx\) and \(v=\frac{1}{2}e^{2x}\), so \(\int_0^1x^2e^{2x}\,dx=[\frac{1}{2}x^2e^{2x}]_0^1-\int_0^1xe^{2x}\,dx\). 2. For the remaining integral, use \(u=x\) and \(dv=e^{2x}\,dx\): \(\int xe^{2x}\,dx=\frac{1}{2}xe^{2x}-\frac{1}{4}e^{2x}\). 3. An antiderivative of the original integrand is \(F(x)=\left(\frac{1}{2}x^2-\frac{1}{2}x+\frac{1}{4}\right)e^{2x}\). 4. Evaluate: \(F(1)-F(0)=\frac{1}{4}e^2-\frac{1}{4}=\frac{e^2-1}{4}\).

Answer

\(\frac{e^2-1}{4}\)
52509012
Evaluate \(\int_{0}^{\frac{\pi}{2}}x^2\cos(x) \, dx\) by applying integration by parts twice.

Hints

- Differentiate the polynomial factor to lower its degree. - Apply integration by parts again to the remaining product. - Track the signs when integrating sine. - Use the sine and cosine values at \(0\) and \(\frac{\pi}{2}\).

Solution

1. Choose \(u=x^2\) and \(dv=\cos(x)\,dx\). Then \(du=2x\,dx\) and \(v=\sin(x)\): \(\int_0^{\frac{\pi}{2}}x^2\cos(x)\,dx=[x^2\sin(x)]_0^{\frac{\pi}{2}}-\int_0^{\frac{\pi}{2}}2x\sin(x)\,dx\). 2. For the remaining integral, choose \(u=2x\) and \(dv=\sin(x)\,dx\). Then \(du=2\,dx\) and \(v=-\cos(x)\), so \(\int 2x\sin(x)\,dx=-2x\cos(x)+2\sin(x)\). 3. An antiderivative of the original integrand is \(F(x)=x^2\sin(x)+2x\cos(x)-2\sin(x)\). 4. Evaluate: \(F(\frac{\pi}{2})-F(0)=\frac{\pi^2}{4}-2\).

Answer

\(\frac{\pi^2}{4}-2\)
53017812
Use integration by parts to evaluate exactly: \(\int_1^e x^2\ln(x) \, dx\).

Hints

- Choose the factor that becomes simpler when differentiated. - Use the integration-by-parts formula. - Recall the values of \(\ln(e)\) and \(\ln(1)\). - Combine like terms at the end.

Solution

1. Let \(u=\ln(x)\) and \(dv=x^2\,dx\). Then \(du=\frac{1}{x}\,dx\) and \(v=\frac{x^3}{3}\). 2. Integration by parts gives \(\int x^2\ln(x)\,dx=\frac{x^3}{3}\ln(x)-\frac{1}{3}\int x^2\,dx\) \(=\frac{x^3}{3}\ln(x)-\frac{x^3}{9}\). 3. Evaluate from \(1\) to \(e\): \(\left[\frac{x^3}{3}\ln(x)-\frac{x^3}{9}\right]_1^e=\left(\frac{e^3}{3}-\frac{e^3}{9}\right)-\left(0-\frac{1}{9}\right)\) \(=\frac{2e^3+1}{9}\).

Answer

\(\frac{2e^3+1}{9}\)
53018312
Use integration by parts to evaluate \(\int_0^1(2x+1)e^{-x}\,dx\).

Hints

- Differentiate the linear factor. - Be careful when finding an antiderivative of \(e^{-x}\). - Apply the bounds to each term carefully. - Simplify the exponential values at the end.

Solution

1. Let \(u=2x+1\) and \(dv=e^{-x}\,dx\). Then \(du=2\,dx\) and \(v=-e^{-x}\). 2. Apply integration by parts: \(\int_0^1(2x+1)e^{-x}\,dx=[-(2x+1)e^{-x}]_0^1+2\int_0^1e^{-x}\,dx\). 3. Evaluate: \([-(2x+1)e^{-x}]_0^1+[-2e^{-x}]_0^1\) \(=\left(-\frac{3}{e}+1\right)+\left(-\frac{2}{e}+2\right)=3-\frac{5}{e}\).

Answer

\(3-\frac{5}{e}\approx 1.1606\)
53018512
Let \(I=\int_0^1(2x+4)e^{0.5x}\,dx\). a) Suppose you use integration by parts with \(u=e^{0.5x}\) and \(dv=(2x+4)\,dx\). Describe what happens to the degree of the polynomial factor in the new integral. b) Choose a more effective assignment for \(u\) and \(dv\), and evaluate \(I\) exactly.

Hints

- Differentiate the factor that becomes simpler. - Compare what differentiation and integration do to a polynomial degree. - The goal is to make the remaining integral easier than the original.

Solution

1. For a), if \(u=e^{0.5x}\) and \(dv=(2x+4)\,dx\), then \(du=0.5e^{0.5x}\,dx\) and \(v=x^2+4x\). The new integral contains the quadratic factor \(x^2+4x\), so the polynomial degree increases from \(1\) to \(2\). 2. For b), choose \(u=2x+4\) and \(dv=e^{0.5x}\,dx\). Then \(du=2\,dx\) and \(v=2e^{0.5x}\). 3. Apply integration by parts: \(I=[(2x+4)2e^{0.5x}]_0^1-4\int_0^1e^{0.5x}\,dx\). 4. Evaluate: \(I=[4(x+2)e^{0.5x}]_0^1-[8e^{0.5x}]_0^1\) \(=(12\sqrt e-8)-(8\sqrt e-8)=4\sqrt e\).

Answer

a) The polynomial degree increases from \(1\) to \(2\). b) \(I=4\sqrt e\)
53018912
Find one antiderivative \(F\) of the integrand, then evaluate \(\int_1^e x\ln(x)\,dx\).

Hints

- Differentiate the logarithmic factor. - Apply integration by parts. - Use \(\ln(e)=1\) and \(\ln(1)=0\).

Solution

1. Let \(u=\ln(x)\) and \(dv=x\,dx\). Then \(du=\frac{1}{x}\,dx\) and \(v=\frac{x^2}{2}\). 2. Integration by parts gives \(F(x)=\frac{x^2}{2}\ln(x)-\frac{1}{2}\int x\,dx\) \(=\frac{x^2}{2}\ln(x)-\frac{x^2}{4}\). 3. Evaluate: \(F(e)-F(1)=\frac{e^2}{4}-\left(-\frac{1}{4}\right)=\frac{e^2+1}{4}\).

Answer

One antiderivative is \(F(x)=\frac{x^2}{2}\ln(x)-\frac{x^2}{4}\). The integral equals \(\frac{e^2+1}{4}\).
53019112
Use integration by parts to evaluate \(\int_0^\pi\cos^2(x)\,\text{d}x\). Arrange the work so that the original integral reappears, then solve for it.

Hints

- View \(\cos^2(x)\) as a product of two cosine factors. - Use \(\sin^2(x)+\cos^2(x)=1\). - Solve algebraically when the original integral appears on both sides. - Use the endpoint values of sine and cosine.

Solution

1. Using integration by parts with \(u=\cos(x)\) and \(dv=\cos(x)\,dx\), let \(I=\int\cos^2(x)\,dx\). Then \(I=\sin(x)\cos(x)+\int\sin^2(x)\,dx\). 2. Since \(\sin^2(x)=1-\cos^2(x)\), \(I=\sin(x)\cos(x)+x-I\). Therefore, \(I=\frac{1}{2}(x+\sin(x)\cos(x))\). 3. Evaluate from \(0\) to \(\pi\): \(\left[\frac{1}{2}(x+\sin(x)\cos(x))\right]_0^\pi=\frac{\pi}{2}\).

Answer

\(\frac{\pi}{2}\)
53025312
Let \(f(x)=(x^2-2x)e^x\). 1) Use integration by parts twice to find one antiderivative of \(f\). 2) Evaluate \(\int_0^2 f(x)\,\text{d}x\). 3) Determine the geometric area between the graph of \(f\) and the x-axis on \([0,2]\), and explain why it differs from the signed integral.

Hints

- Differentiate the polynomial factor so its degree decreases at each application of integration by parts. - Keep the common factor \(e^x\) when simplifying the antiderivative. - Determine the sign of \(x(x-2)e^x\) on the interval before converting signed accumulation to geometric area.

Solution

1. Apply integration by parts to \(\int(x^2-2x)e^x\,\text{d}x\) with \(u=x^2-2x\) and \(\text{d}v=e^x\,\text{d}x\). Then \(\text{d}u=(2x-2)\,\text{d}x\) and \(v=e^x\), so \(\int(x^2-2x)e^x\,\text{d}x=(x^2-2x)e^x-\int(2x-2)e^x\,\text{d}x\). 2. Apply integration by parts again to the remaining integral. An antiderivative is \(F(x)=(x^2-4x+4)e^x\). 3. Therefore, \(\int_0^2 f(x)\,\text{d}x=F(2)-F(0)=0-4=-4\). 4. On \([0,2]\), \(x(x-2)\le0\) and \(e^x>0\), so \(f(x)\le0\). The signed integral is negative, while geometric area is positive. Thus, the area is \(|-4|=4\) square units.

Answer

1) One antiderivative is \(F(x)=(x^2-4x+4)e^x\). 2) \(-4\) 3) \(4\) square units; the function is nonpositive on \([0,2]\), so the geometric area is the absolute value of the signed integral.
53468412
Find the area between the graph of \(f(x)=\ln(x)\) and the \(x\)-axis on \(\left[\frac{1}{e},e\right]\).
Figure for problem 534684

Hints

- Find where the natural logarithm crosses the \(x\)-axis. - Use integration by parts to find an antiderivative of \(\ln(x)\). - Take the magnitude of the signed integral on the interval below the axis.

Solution

1. The graph crosses the \(x\)-axis where \(\ln(x)=0\), so split the interval at \(x=1\). 2. Use integration by parts to find an antiderivative: \(\int\ln(x)\,dx=x\ln(x)-x+C\). 3. On \(\left[\frac{1}{e},1\right]\), the graph lies below the axis. The signed integral is \([x\ln(x)-x]_{1/e}^{1}=-1+\frac{2}{e}\), so the area is \(A_1=1-\frac{2}{e}\). 4. On \([1,e]\), the graph lies above the axis, and \(A_2=[x\ln(x)-x]_{1}^{e}=1\). 5. Therefore, \(A=1-\frac{2}{e}+1=2-\frac{2}{e}\approx 1.264\) square units.

Answer

The area is \(2-\frac{2}{e}\approx 1.264\) square units.
54914812
Find an antiderivative of \(\arctan(x)\) by treating the integrand as a product with \(1\).

Hints

- View the single function as one factor multiplied by a constant function. - Differentiate the factor whose derivative becomes a rational expression. - After applying integration by parts, look for a denominator-derivative relationship.

Solution

1. Let \(u=\arctan(x)\) and \(\text{d}v=\text{d}x\), so \(\text{d}u=\frac{1}{1+x^2}\,\text{d}x\) and \(v=x\). 2. Integration by parts gives \(x\arctan(x)-\int\frac{x}{1+x^2}\,\text{d}x\). 3. The remaining integral is \(\frac{1}{2}\ln(1+x^2)\). 4. The antiderivative is \(x\arctan(x)-\frac{1}{2}\ln(1+x^2)+C\).

Answer

\(x\arctan(x)-\frac{1}{2}\ln(1+x^2)+C\)
54914912
Find an antiderivative of \(\arcsin(x)\) for \(-1<x<1\) by treating the integrand as a product with \(1\).

Hints

- View the single inverse-trigonometric function as a product with \(1\). - Differentiate \(\arcsin(x)\) and integrate the constant factor. - In the remaining radical integral, compare the numerator with the derivative of \(1-x^2\).

Solution

1. Let \(u=\arcsin(x)\) and \(\text{d}v=\text{d}x\). Then \(\text{d}u=\frac{1}{\sqrt{1-x^2}}\,\text{d}x\) and \(v=x\). 2. Integration by parts gives \(x\arcsin(x)-\int\frac{x}{\sqrt{1-x^2}}\,\text{d}x\). 3. For the remaining integral, let \(w=1-x^2\). Then \(\int\frac{x}{\sqrt{1-x^2}}\,\text{d}x=-\sqrt{1-x^2}\). 4. Therefore, an antiderivative is \(x\arcsin(x)+\sqrt{1-x^2}+C\).

Answer

\(x\arcsin(x)+\sqrt{1-x^2}+C\)
54915112
Evaluate \(\int x^2\cos(x)\,\text{d}x\). Apply integration by parts twice and show both applications.

Hints

- In the first application, differentiate \(x^2\) and integrate \(\cos(x)\). - The remaining integral still contains a product, so apply integration by parts again. - Differentiate the final expression to check cancellation of the extra terms.

Solution

1. Let \(u=x^2\) and \(\text{d}v=\cos(x)\,\text{d}x\). Then \(\text{d}u=2x\,\text{d}x\) and \(v=\sin(x)\). 2. The first application gives \(x^2\sin(x)-2\int x\sin(x)\,\text{d}x\). 3. For the remaining integral, let \(u=x\) and \(\text{d}v=\sin(x)\,\text{d}x\). Then \(\int x\sin(x)\,\text{d}x=-x\cos(x)+\sin(x)\). 4. Substitution gives \(x^2\sin(x)+2x\cos(x)-2\sin(x)+C\).

Answer

\(x^2\sin(x)+2x\cos(x)-2\sin(x)+C\)
54915212
Use integration by parts to evaluate exactly: \(\int_0^1\ln(x+1)\,\text{d}x\).

Hints

- Treat the logarithm as one factor and pair it with \(1\). - After integration by parts, rewrite \(x/(x+1)\) as a constant minus a reciprocal term. - Evaluate the logarithmic boundary values exactly.

Solution

1. Let \(u=\ln(x+1)\) and \(\text{d}v=\text{d}x\). Then \(\text{d}u=\frac{1}{x+1}\,\text{d}x\) and \(v=x\). 2. Integration by parts gives \(\int_0^1\ln(x+1)\,\text{d}x=[x\ln(x+1)]_0^1-\int_0^1\frac{x}{x+1}\,\text{d}x\). 3. Rewrite \(\frac{x}{x+1}=1-\frac{1}{x+1}\). Therefore, \(\int_0^1\frac{x}{x+1}\,\text{d}x=[x-\ln(x+1)]_0^1=1-\ln2\). 4. The boundary term is \(\ln2\), so the integral equals \(\ln2-(1-\ln2)=2\ln2-1\).

Answer

\(2\ln2-1\)
54915312
Evaluate \(\int x^2e^x\,\text{d}x\) by applying integration by parts twice.

Hints

- Differentiate the polynomial factor so its degree decreases. - Apply integration by parts again to the remaining linear–exponential product. - Factor out \(e^x\) when simplifying the result.

Solution

1. Let \(u=x^2\) and \(\text{d}v=e^x\,\text{d}x\). Then \(\text{d}u=2x\,\text{d}x\) and \(v=e^x\). 2. The first application gives \(x^2e^x-2\int xe^x\,\text{d}x\). 3. Apply integration by parts again to \(\int xe^x\,\text{d}x\): \(\int xe^x\,\text{d}x=xe^x-e^x\). 4. Substitute and simplify: \(x^2e^x-2(xe^x-e^x)=e^x(x^2-2x+2)+C\).

Answer

\(e^x(x^2-2x+2)+C\)
54915512
Evaluate \(\int x\arctan(x)\,\text{d}x\).

Hints

- Differentiate the inverse-tangent factor and integrate \(x\). - Rewrite the resulting rational expression by comparing its numerator with its denominator. - Combine the two inverse-tangent terms after integration.

Solution

1. Let \(u=\arctan(x)\) and \(\text{d}v=x\,\text{d}x\). Then \(\text{d}u=\frac{1}{1+x^2}\,\text{d}x\) and \(v=\frac{x^2}{2}\). 2. Integration by parts gives \(\frac{x^2}{2}\arctan(x)-\frac{1}{2}\int\frac{x^2}{1+x^2}\,\text{d}x\). 3. Rewrite \(\frac{x^2}{1+x^2}=1-\frac{1}{1+x^2}\). 4. Therefore, the antiderivative is \(\frac{x^2}{2}\arctan(x)-\frac{x}{2}+\frac{1}{2}\arctan(x)+C\), or \(\frac{x^2+1}{2}\arctan(x)-\frac{x}{2}+C\).

Answer

\(\frac{x^2+1}{2}\arctan(x)-\frac{x}{2}+C\)
54915812
Use integration by parts to evaluate exactly: \(\int_0^1 x\ln(x+1)\,\text{d}x\). Simplify the remaining rational expression by polynomial division.

Hints

- Differentiate the logarithmic factor and integrate \(x\). - After integration by parts, divide \(x^2\) by \(x+1\) before integrating. - Keep the boundary term separate until the logarithmic terms cancel.

Solution

1. Let \(u=\ln(x+1)\) and \(\text{d}v=x\,\text{d}x\). Then \(\text{d}u=\frac{1}{x+1}\,\text{d}x\) and \(v=\frac{x^2}{2}\). 2. Integration by parts gives \(\int_0^1x\ln(x+1)\,\text{d}x=\left[\frac{x^2}{2}\ln(x+1)\right]_0^1-\frac{1}{2}\int_0^1\frac{x^2}{x+1}\,\text{d}x\). 3. Divide: \(\frac{x^2}{x+1}=x-1+\frac{1}{x+1}\). Thus, \(\int_0^1\frac{x^2}{x+1}\,\text{d}x=\left[\frac{x^2}{2}-x+\ln(x+1)\right]_0^1=\ln2-\frac{1}{2}\). 4. Therefore, \(\frac{1}{2}\ln2-\frac{1}{2}\left(\ln2-\frac{1}{2}\right)=\frac{1}{4}\).

Answer

\(\frac{1}{4}\)
54915912
Evaluate exactly: \(\int_1^e\frac{\ln(x)}{x^2}\,\text{d}x\).

Hints

- Choose the factor whose derivative becomes simpler. - Keep the endpoint contribution separate from the remaining integral. - Evaluate each exact term before combining them.

Solution

1. Differentiate \(\ln(x)\) and integrate \(x^{-2}\). 2. Integration by parts gives \(\left[-\frac{\ln(x)}{x}\right]_1^e+\int_1^e\frac{1}{x^2}\,\text{d}x\). 3. The boundary term is \(-\frac{1}{e}\), and the remaining integral is \(1-\frac{1}{e}\). 4. The exact value is \(1-\frac{2}{e}\).

Answer

\(1-\frac{2}{e}\)
54916012
Evaluate \(\int x[\ln(x)]^2\,\text{d}x\) for \(x>0\).

Hints

- Which factor becomes simpler each time it is differentiated? - After the first transformation, identify the remaining integral as a simpler version of the same pattern. - Check that the logarithmic terms cancel correctly when you differentiate.

Solution

1. Differentiate \([\ln(x)]^2\) and integrate \(x\). 2. Integration by parts gives \(\frac{x^2}{2}[\ln(x)]^2-\int x\ln(x)\,\text{d}x\). 3. A second application gives \(\int x\ln(x)\,\text{d}x=\frac{x^2}{2}\ln(x)-\frac{x^2}{4}\). 4. Therefore the antiderivative is \(\frac{x^2}{2}[\ln(x)]^2-\frac{x^2}{2}\ln(x)+\frac{x^2}{4}+C\).

Answer

\(\frac{x^2}{2}[\ln(x)]^2-\frac{x^2}{2}\ln(x)+\frac{x^2}{4}+C\)
54916112
A twice-differentiable function \(f\) satisfies \(f(0)=2\), \(f(1)=5\), and \(f'(1)=4\). Find \(\int_0^1 x f''(x)\,\text{d}x\).

Hints

- Treat the variable multiplying the second derivative as one factor. - The remaining integral can be determined from endpoint values. - Pay attention to the lower endpoint in the boundary product.

Solution

1. Integration by parts gives \(\int_0^1x f''(x)\,\text{d}x=[xf'(x)]_0^1-\int_0^1f'(x)\,\text{d}x\). 2. The boundary product is \(f'(1)=4\). 3. The remaining integral is \(f(1)-f(0)=5-2=3\). 4. The requested value is \(4-3=1\).

Answer

\(1\)
54916212
A differentiable function \(g\) satisfies \(g(0)=1\), \(g(2)=5\), and \(\int_0^2 xg'(x)\,\text{d}x=7\). Find \(\int_0^2 g(x)\,\text{d}x\).

Hints

- Transform the integral containing the derivative into a boundary term and an integral without the derivative. - Evaluate the boundary expression before solving for the unknown integral. - Use the given integral value as part of an equation.

Solution

1. Integration by parts gives \(\int_0^2xg'(x)\,\text{d}x=[xg(x)]_0^2-\int_0^2g(x)\,\text{d}x\). 2. The boundary product is \(2g(2)-0g(0)=10\). 3. Substitute the given value: \(7=10-\int_0^2g(x)\,\text{d}x\). 4. Therefore \(\int_0^2g(x)\,\text{d}x=3\).

Answer

\(3\)
54916312
Use integration by parts to evaluate exactly: \(\int_0^1\arctan(x)\,\text{d}x\).

Hints

- Treat the inverse-tangent function as a product with \(1\). - After integration by parts, compare the remaining numerator with the derivative of \(1+x^2\). - Use \(\arctan(1)=\pi/4\) and \(\arctan(0)=0\).

Solution

1. Let \(u=\arctan(x)\) and \(\text{d}v=\text{d}x\). Then \(\text{d}u=\frac{1}{1+x^2}\,\text{d}x\) and \(v=x\). 2. Integration by parts gives \(\int_0^1\arctan(x)\,\text{d}x=[x\arctan(x)]_0^1-\int_0^1\frac{x}{1+x^2}\,\text{d}x\). 3. The boundary term is \(\frac{\pi}{4}\), and \(\int_0^1\frac{x}{1+x^2}\,\text{d}x=\frac{1}{2}\ln2\). 4. Therefore, the exact value is \(\frac{\pi}{4}-\frac{1}{2}\ln2\).

Answer

\(\frac{\pi}{4}-\frac{1}{2}\ln2\)
54916412
Evaluate \(\int\ln(1+x^2)\,\text{d}x\) using integration by parts.

Hints

- Treat the logarithm as one factor multiplied by \(1\). - After integration by parts, rewrite the rational expression as a constant minus \(1/(1+x^2)\). - Differentiate the final expression to check the cancellation of the rational terms.

Solution

1. Let \(u=\ln(1+x^2)\) and \(\text{d}v=\text{d}x\). Then \(\text{d}u=\frac{2x}{1+x^2}\,\text{d}x\) and \(v=x\). 2. Integration by parts gives \(x\ln(1+x^2)-2\int\frac{x^2}{1+x^2}\,\text{d}x\). 3. Rewrite \(\frac{x^2}{1+x^2}=1-\frac{1}{1+x^2}\). 4. Therefore, the antiderivative is \(x\ln(1+x^2)-2x+2\arctan(x)+C\).

Answer

\(x\ln(1+x^2)-2x+2\arctan(x)+C\)
54916512
Find the constant \(k\) for which \(\int_0^1(x-k)e^x\,\text{d}x=0\).

Hints

- Separate the term containing the unknown constant. - One of the definite integrals requires integration by parts. - After evaluating both integrals, solve the resulting linear equation.

Solution

1. Split the integral as \(\int_0^1xe^x\,\text{d}x-k\int_0^1e^x\,\text{d}x\). 2. Integration by parts gives \(\int_0^1xe^x\,\text{d}x=[xe^x]_0^1-\int_0^1e^x\,\text{d}x=1\). 3. Also, \(\int_0^1e^x\,\text{d}x=e-1\). 4. The condition becomes \(1-k(e-1)=0\), so \(k=\frac{1}{e-1}\).

Answer

\(k=\frac{1}{e-1}\)
52507212
Let \(f(x)=[\ln(x)]^2\) for \(x>0\). Use the accumulation function \(I_1(x)=\int_1^x[\ln(t)]^2 \, dt\) and repeated integration by parts to find an antiderivative of \(f\).

Hints

- Apply integration by parts more than once. - Differentiating a power of \(\ln(t)\) lowers that power. - Track the signs when substituting the second integration-by-parts result. - Evaluate all logarithmic terms at the lower limit \(1\).

Solution

1. Use integration by parts with \(u=[\ln(t)]^2\) and \(dv=dt\). Then \(du=\frac{2\ln(t)}{t}\,dt\) and \(v=t\). 2. Therefore, \(\int[\ln(t)]^2\,dt=t[\ln(t)]^2-2\int\ln(t)\,dt\). 3. Apply integration by parts again to \(\int\ln(t)\,dt\), obtaining \(t\ln(t)-t\). 4. An antiderivative is \(t[\ln(t)]^2-2t\ln(t)+2t\). 5. Evaluate from \(1\) to \(x\). Since \(\ln(1)=0\), \(I_1(x)=x[\ln(x)]^2-2x\ln(x)+2x-2\).

Answer

\(I_1(x)=x[\ln(x)]^2-2x\ln(x)+2x-2\)
52508412
Evaluate \(\int_{0}^{\pi}e^x\sin(x) \, dx\). Apply integration by parts repeatedly until the original integral reappears, then solve for it.

Hints

- Apply integration by parts more than once. - Track the signs when differentiating cosine. - When the original integral returns, move it to the same side of the equation. - Use the sine and cosine values at \(0\) and \(\pi\).

Solution

1. Let \(I=\int_0^\pi e^x\sin(x)\,dx\). Use integration by parts with \(u=\sin(x)\) and \(dv=e^x\,dx\): \(I=[e^x\sin(x)]_0^\pi-\int_0^\pi e^x\cos(x)\,dx\). The boundary term is \(0\), so \(I=-\int_0^\pi e^x\cos(x)\,dx\). 2. Apply integration by parts to the remaining integral with \(u=\cos(x)\) and \(dv=e^x\,dx\): \(\int_0^\pi e^x\cos(x)\,dx=[e^x\cos(x)]_0^\pi+I\). 3. Substitute into the first equation: \(I=-[e^x\cos(x)]_0^\pi-I\). Thus \(2I=-[e^x\cos(x)]_0^\pi\). 4. Evaluate the boundary term: \(-[e^\pi\cos(\pi)-e^0\cos(0)]=e^\pi+1\). Therefore, \(I=\frac{e^\pi+1}{2}\).

Answer

\(\frac{e^\pi+1}{2}\)
53018612
Evaluate exactly: \(\int_1^e(\ln(x))^2\,dx\). Use integration by parts more than once by viewing the integrand as \(1\cdot(\ln(x))^2\).

Hints

- Insert a factor of \(1\) to create a product. - Apply integration by parts again to the remaining logarithmic integral. - Track the minus sign carefully. - Recall the derivative of \(\ln(x)\).

Solution

1. Let \(u=(\ln(x))^2\) and \(dv=dx\). Then \(du=\frac{2\ln(x)}{x}\,dx\) and \(v=x\). 2. Thus, \(\int(\ln(x))^2\,dx=x(\ln(x))^2-2\int\ln(x)\,dx\). 3. Apply integration by parts again to \(\int\ln(x)\,dx\): \(\int\ln(x)\,dx=x\ln(x)-x\). 4. Therefore, an antiderivative is \(F(x)=x(\ln(x))^2-2x\ln(x)+2x\). 5. Evaluate: \([F(x)]_1^e=e-2\).

Answer

\(e-2\)
53018712
Use integration by parts repeatedly to evaluate \(\int_0^\pi(x^2-2x)\sin(x)\,dx\).

Hints

- Differentiate the polynomial factor so its degree decreases. - Apply integration by parts twice. - Track the signs when integrating sine and cosine. - Use the exact trigonometric values at \(0\) and \(\pi\).

Solution

1. Let \(u=x^2-2x\) and \(dv=\sin(x)\,dx\). Then \(du=(2x-2)\,dx\) and \(v=-\cos(x)\). 2. Therefore, \(\int(x^2-2x)\sin(x)\,dx=-(x^2-2x)\cos(x)+\int(2x-2)\cos(x)\,dx\). 3. Apply integration by parts again with \(u=2x-2\) and \(dv=\cos(x)\,dx\): \(\int(2x-2)\cos(x)\,dx=(2x-2)\sin(x)+2\cos(x)\). 4. An antiderivative is \(F(x)=-(x^2-2x)\cos(x)+(2x-2)\sin(x)+2\cos(x)\). 5. Evaluate: \(F(\pi)=\pi^2-2\pi-2\) and \(F(0)=2\), so the integral is \(\pi^2-2\pi-4\).

Answer

\(\pi^2-2\pi-4\approx -0.414\)
53018812
Use integration by parts twice to evaluate exactly. After the second application, the original integral will reappear. \(\int_0^{\frac{\pi}{2}}e^{2x}\cos(x)\,dx\)

Hints

- Differentiate the exponential factor and integrate the trigonometric factor twice. - Treat the recurring integral as an unknown quantity. - Solve the resulting equation for that integral. - Use the exact sine and cosine values at the bounds.

Solution

1. Let \(I=\int e^{2x}\cos(x)\,dx\). With \(u=e^{2x}\) and \(dv=\cos(x)\,dx\), \(I=e^{2x}\sin(x)-2\int e^{2x}\sin(x)\,dx\). 2. Apply integration by parts to the remaining integral: \(\int e^{2x}\sin(x)\,dx=-e^{2x}\cos(x)+2I\). 3. Substitute this expression: \(I=e^{2x}\sin(x)+2e^{2x}\cos(x)-4I\). Thus, \(I=\frac{1}{5}e^{2x}(\sin(x)+2\cos(x))\). 4. Evaluate from \(0\) to \(\frac{\pi}{2}\): \(\frac{1}{5}e^\pi-\frac{2}{5}=\frac{e^\pi-2}{5}\).

Answer

\(\frac{e^\pi-2}{5}\approx 4.228\)
54915612
Find constants \(a\), \(b\), and \(c\) such that \(\frac{\text{d}}{\text{d}x}\left[e^{2x}(ax^2+bx+c)\right]=e^{2x}(3x^2-4x+5)\). Then use your result to evaluate \(\int e^{2x}(3x^2-4x+5)\,\text{d}x\).

Hints

- Differentiate the entire product before comparing it with the given expression. - Organize the result by powers of the variable. - The coefficients of matching powers must agree.

Solution

1. Differentiate the proposed product to obtain \(e^{2x}[2ax^2+(2b+2a)x+(2c+b)]\). 2. Match coefficients with \(e^{2x}(3x^2-4x+5)\): \(2a=3\), \(2b+2a=-4\), and \(2c+b=5\). 3. Solving gives \(a=\frac{3}{2}\), \(b=-\frac{7}{2}\), and \(c=\frac{17}{4}\). 4. Therefore the integral is \(e^{2x}\left(\frac{3}{2}x^2-\frac{7}{2}x+\frac{17}{4}\right)+C\).

Answer

\(a=\frac{3}{2}\), \(b=-\frac{7}{2}\), and \(c=\frac{17}{4}\) \(\int e^{2x}(3x^2-4x+5)\,\text{d}x=e^{2x}\left(\frac{3}{2}x^2-\frac{7}{2}x+\frac{17}{4}\right)+C\)
54916612
Evaluate \(\int\frac{\ln(x)}{(1+x)^2}\,\text{d}x\) for \(x>0\).

Hints

- Choose the logarithm as the factor to differentiate. - After the first transformation, rewrite the remaining rational expression as simpler fractions. - Use the stated domain when simplifying logarithmic absolute values.

Solution

1. Differentiate \(\ln(x)\) and integrate \((1+x)^{-2}\). 2. Integration by parts gives \(-\frac{\ln(x)}{1+x}+\int\frac{1}{x(1+x)}\,\text{d}x\). 3. Decompose \(\frac{1}{x(1+x)}=\frac{1}{x}-\frac{1}{1+x}\). 4. The antiderivative is \(-\frac{\ln(x)}{1+x}+\ln(x)-\ln(1+x)+C\).

Answer

\(-\frac{\ln(x)}{1+x}+\ln(x)-\ln(1+x)+C\)

All problems may be used, copied and printed free of charge for school and tutoring, including paid tutoring. Commercial adaptations as well as publication or redistribution on the internet are not permitted.