Calculus: Early Transcendentals 9th Edition

Published by Cengage Learning
ISBN 10: 1337613924
ISBN 13: 978-1-33761-392-7

Chapter 7 - Section 7.4 - Integration of Rational Functions by Partial Fractions. - 7.4 Exercises - Page 515: 32

Answer

$\frac{1}{2}\ln \left( {\frac{{18}}{{13}}} \right) - \frac{\pi }{6} + \frac{2}{3}\arctan \left( {\frac{2}{3}} \right)$

Work Step by Step

$$\eqalign{ & \int_0^1 {\frac{x}{{{x^2} + 4x + 4 + 9}}} dx \cr & \int_0^1 {\frac{x}{{{{\left( {x + 2} \right)}^2} + 9}}} dx \cr & {\text{Integrate by substitution}} \cr & {\text{Let }}u = x + 2,{\text{ }}du = dx \cr & {\text{The new limitsof integration are}} \cr & x = 1 \to u = 3 \cr & x = 0 \to u = 2 \cr & {\text{Substituting}} \cr & \int_0^1 {\frac{x}{{{{\left( {x + 2} \right)}^2} + 9}}} dx = \int_2^3 {\frac{{u - 2}}{{{u^2} + 9}}du} \cr & = \int_2^3 {\left( {\frac{u}{{{u^2} + 9}} - \frac{2}{{{u^2} + 9}}} \right)du} \cr & {\text{Integrating}} \cr & = \left[ {\frac{1}{2}\ln \left( {{u^2} + 9} \right) - \frac{2}{3}\arctan \left( {\frac{u}{3}} \right)} \right]_2^3 \cr & {\text{Evaluating}} \cr & {\text{ = }}\left[ {\frac{1}{2}\ln \left( {{{\left( 3 \right)}^2} + 9} \right) - \frac{2}{3}\arctan \left( {\frac{3}{3}} \right)} \right] \cr & - \left[ {\frac{1}{2}\ln \left( {{{\left( 2 \right)}^2} + 9} \right) - \frac{2}{3}\arctan \left( {\frac{2}{3}} \right)} \right] \cr & {\text{ = }}\frac{1}{2}\ln \left( {18} \right) - \frac{2}{3}\left( {\frac{\pi }{4}} \right) - \frac{1}{2}\ln \left( {13} \right) + \frac{2}{3}\arctan \left( {\frac{2}{3}} \right) \cr & {\text{ = }}\frac{1}{2}\ln \left( {\frac{{18}}{{13}}} \right) - \frac{\pi }{6} + \frac{2}{3}\arctan \left( {\frac{2}{3}} \right) \cr & \approx 0.031114 \cr} $$
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