Calculus (3rd Edition)

Published by W. H. Freeman
ISBN 10: 1464125260
ISBN 13: 978-1-46412-526-3

Chapter 8 - Techniques of Integration - Chapter Review Exercises - Page 460: 66

Answer

$\pi$

Work Step by Step

$V$ = $\int_1^{e}2\pi{x}·[\ln{x}-(\ln{x})^{2}]dx$ = $2\pi{\int_1^{e}x\ln{x}dx}$ - $2\pi{\int_1^{e}x(\ln{x})^{2}dx}$ use integration by parts $u$ = $(\ln{x})^{2}$ $u'$ = $\frac{2\ln{x}}{x}$ $v'$ = $x$ $v$ = $\frac{x^{2}}{2}$ $V$ = $2\pi{\int_1^{e}x\ln{x}dx}$ - $2\pi(\frac{1}{2}x^{2})(\ln{x})^{2}|_1^e$ - $\int_1^{e}x\ln{x}dx$ = $-\pi{e^{2}}+4\pi{\int_1^{e}x\ln{x}dx}$ use integration by parts again $u$ = $\ln{x}$ $u'$ = $\frac{1}{x}$ $v'$ = $x$ $v$ = $\frac{x^{2}}{2}$ $V$ = $-\pi{e^{2}}+4\pi[(\frac{1}{2}x^{2})\ln{x}|_1^e-\frac{1}{2}\int_1^e{{xdx}}]$ = $\pi$
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