Thomas' Calculus 13th Edition

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

Chapter 8: Techniques of Integration - Section 8.8 - Improper Integrals - Exercises 8.8 - Page 501: 19

Answer

$$\ln \left(1+\frac{\pi}{2}\right)$$

Work Step by Step

\begin{align*} \int_{0}^{\infty} \frac{d v}{\left(1+v^{2}\right)\left(1+\tan ^{-1} v\right)}&=\int_{0}^{\infty} \frac{\frac{1}{\left(1+v^{2}\right)}d v}{\left(1+\tan ^{-1} v\right)}\\ &=\lim _{b \rightarrow \infty}\left[\ln \left|1+\tan ^{-1} v\right|\right]_{0}^{b}\\ &=\lim _{b \rightarrow \infty}\left[\ln \left|1+\tan ^{-1} b\right|-\ln \left|1+\tan ^{-1} 0\right|\right]\\ &=\ln \left(1+\frac{\pi}{2}\right)-\ln (1+0)\\ &=\ln \left(1+\frac{\pi}{2}\right) \end{align*}
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