Calculus (3rd Edition)

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

Chapter 6 - Applications of the Integral - 6.4 The Method of Cylindrical Shells - Exercises - Page 312: 31

Answer

$\frac{602\pi}{5}$

Work Step by Step

$V$ = $2\pi\int_0^{5}2ydy+2\pi\int_5^{9}y\sqrt {9-y}dy$ $2\pi\int_0^{5}2ydy$ = $2\pi(y^{2})|_0^5$ = $50\pi$ $2\pi\int_5^{9}y\sqrt {9-y}dy$ let $u$ = $9-y$ $du$ = $-dy$ $2\pi\int_5^{9}y\sqrt {9-y}dy$ = $2\pi\int_0^{4}(9-u)\sqrt {u}du$ = $2\pi\int_0^{4}(9u^{\frac{1}{2}}-u^{\frac{3}{2}})du$ = $2\pi(6u^{\frac{3}{2}}-\frac{2}{5}u^{\frac{5}{2}})|_0^4$ = $\frac{352\pi}{5}$ Total volume = $50\pi+\frac{352\pi}{5}$ = $\frac{602\pi}{5}$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.