Thomas' Calculus 13th Edition

Published by Pearson
ISBN 10: 0-32187-896-5
ISBN 13: 978-0-32187-896-0

Chapter 7: Transcendental Functions - Section 7.6 - Inverse Trigonometric Functions - Exercises 7.6 - Page 421: 77

Answer

$$x + \ln \left( {{x^2} + 9} \right) - \frac{{10}}{3}{\tan ^{ - 1}}\left( {\frac{x}{3}} \right) + C$$

Work Step by Step

$$\eqalign{ & \int {\frac{{{x^2} + 2x - 1}}{{{x^2} + 9}}} dx \cr & {\text{simplify the improper fraction }}\frac{{{x^2} + 2x - 1}}{{{x^2} + 9}} \cr & \frac{{{x^2} + 2x - 1}}{{{x^2} + 9}} = 1 + \frac{{2x - 10}}{{{x^2} + 9}} \cr & \frac{{{x^2} + 2x - 1}}{{{x^2} + 9}} = 1 + \frac{{2x}}{{{x^2} + 9}} - \frac{{10}}{{{x^2} + 9}} \cr & {\text{then}} \cr & \int {\frac{{{x^2} + 2x - 1}}{{{x^2} + 9}}} dx = \int {\left( {1 + \frac{{2x}}{{{x^2} + 9}} - \frac{{10}}{{{x^2} + 9}}} \right)} dx \cr & {\text{sum rule for integrals gives}} \cr & = \int {dx} + \int {\frac{{2x}}{{{x^2} + 9}}} dx - \int {\frac{{10}}{{{x^2} + 9}}} dx \cr & {\text{integrate by using the formulas}} \cr & \int {\frac{{du}}{u}} = \ln \left| u \right| + C{\text{ and }}\int {\frac{1}{{{u^2} + {a^2}}}} = \frac{1}{a}{\tan ^{ - 1}}\left( {\frac{x}{a}} \right) + C \cr & {\text{then}} \cr & = x + \ln \left( {{x^2} + 9} \right) - \frac{{10}}{3}{\tan ^{ - 1}}\left( {\frac{x}{3}} \right) + C \cr} $$
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