Multivariable Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 0-53849-787-4
ISBN 13: 978-0-53849-787-9

Chapter 13 - Vector Functions - 13.2 Exercises - Page 877: 36

Answer

$\pi \mathrm{j}+(\ln 2)\mathrm{k}$

Work Step by Step

Use the last boxed formula of this section: $\displaystyle \int_{0}^{1}(\frac{4}{1+t^{2}}\mathrm{j}+\frac{2t}{1+t^{2}}\mathrm{k})dt=(\int_{0}^{1}\frac{4}{1+t^{2}}dt)\mathrm{j}+(\int_{0}^{1}\frac{2t}{1+t^{2}}dt)\mathrm{k}$ ... the first integral is found in tables .... arctan(t)+C ... the second integral has form $\displaystyle \frac{du}{u}$, where $u=1+t^{2},\quad(du=2tdt)$ $=[4\tan^{-1}t]_{0}^{1}\mathrm{j}+[\ln(1+t^{2})]_{0}^{1}\mathrm{k}$ $=[4\tan^{-1}1-4\tan^{-1}0]\mathrm{j} +[\ln 2 +\ln 1]\mathrm{k}$ $=4(\displaystyle \frac{\pi}{4}-0)\mathrm{j}+(\ln 2-0)\mathrm{k}$ $=\pi \mathrm{j}+\ln 2\mathrm{k}$
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