Calculus 8th Edition

Published by Cengage
ISBN 10: 1285740629
ISBN 13: 978-1-28574-062-1

Chapter 7 - Techniques of Integration - 7.1 Integration by Parts - 7.1 Exercises - Page 516: 27

Answer

$\displaystyle \frac{4}{5}-\frac{\ln(5)}{5} ≈ 0.478112$

Work Step by Step

Integration by parts formula: $\displaystyle \int fg' $ $\displaystyle dx = fg-\int f'g$ $dx$ $\displaystyle \int_1^5\frac{\ln(R)}{R^2}dR = \int_1^5\ln(R)(\frac{1}{R^2})dR$ ____________________________ Let $\displaystyle f = \ln(R)$ and $\displaystyle g' = \frac{1}{R^2}$ thus $\displaystyle f' = \frac{1}{R}$ and $\displaystyle g = -\frac{1}{R}$ ____________________________ $\displaystyle \int_1^5\ln(R)(\frac{1}{R^2})dR = [\ln(R)(-\frac{1}{R})]_1^5-\int_1^5(-\frac{1}{R})(\frac{1}{R})dR$ $\displaystyle [-\frac{\ln(5)}{5}-(-\frac{\ln(1)}{1})] + \int_1^5\frac{1}{R^2}dR$ $\displaystyle -\frac{\ln(5)}{5} + 0 + (-\frac{1}{R})|^5_1$ $\displaystyle -\frac{\ln(5)}{5} + (-\frac{1}{5} - (-\frac{1}{1}))$ $\displaystyle -\frac{\ln(5)}{5} -\frac{1}{5} + 1$ $\displaystyle \frac{4}{5}-\frac{\ln(5)}{5} ≈ 0.478112$
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