Calculus, 10th Edition (Anton)

Published by Wiley
ISBN 10: 0-47064-772-8
ISBN 13: 978-0-47064-772-1

Chapter 7 - Principles Of Integral Evaluation - 7.4 Trigonometric Substitutions - Exercises Set 7.4 - Page 514: 42

Answer

$$\frac{1}{2}\ln \left( {{{\left( {x + 1} \right)}^2} + 1} \right) - {\tan ^{ - 1}}\left( {x + 1} \right) + C$$

Work Step by Step

$$\eqalign{ & \int {\frac{x}{{{x^2} + 2x + 2}}} dx \cr & {\text{Completing the square for }}{x^2} + 2x + 2 \cr & {x^2} + 2x + 2 = \left( {{x^2} + 2x + 1} \right) + 1 \cr & {x^2} + 2x + 2 = {\left( {x + 1} \right)^2} + 1 \cr & \int {\frac{x}{{{x^2} + 2x + 2}}} dx = \int {\frac{x}{{{{\left( {x + 1} \right)}^2} + 1}}} dx \cr & \cr & {\text{Write in terms of }}u \cr & {\text{Substitute }}u = x + 1,{\text{ }}\,\,\,du = dx{\text{ and }}x = u - 1 \cr & \int {\frac{x}{{{{\left( {x + 1} \right)}^2} + 1}}} dx = \int {\frac{{u - 1}}{{{u^2} + 1}}} du \cr & {\text{Distribute}} \cr & = \int {\frac{u}{{{u^2} + 1}}} du - \int {\frac{1}{{{u^2} + 1}}} du \cr & {\text{Integrate}} \cr & = \frac{1}{2}\ln \left( {{u^2} + 1} \right) - {\tan ^{ - 1}}u + C \cr & \cr & {\text{Write in terms of }}x,\,\,{\text{replace }}u = x + 1 \cr & = \frac{1}{2}\ln \left( {{{\left( {x + 1} \right)}^2} + 1} \right) - {\tan ^{ - 1}}\left( {x + 1} \right) + C \cr} $$
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