Calculus 10th Edition

Published by Brooks Cole
ISBN 10: 1-28505-709-0
ISBN 13: 978-1-28505-709-5

Chapter 8 - Integration Techniques, L'Hopital's Rule, and Improper Integrals - 8.2 Exercises - Page 522: 55

Answer

$$ - 2\sqrt x \cos \sqrt x + 2\sin \sqrt x + C$$

Work Step by Step

$$\eqalign{ & \int {\sin \sqrt x dx} \cr & {\text{Let }}w = \sqrt x ,{\text{ }}dw = \frac{1}{{2\sqrt x }}dx,{\text{ }}dx = 2wdw \cr & \int {\sin \sqrt x } dx = 2\int {w\sin w} dw \cr & {\text{Integrate by parts}} \cr & {\text{Let }}u = 2w \Rightarrow du = 2dw; \cr & dv = \sin wdw \Rightarrow v = - \cos w \cr & {\text{Integration by parts formula}} \cr & 2\int {w\sin w} dw = \underbrace {2w}_u\underbrace {\left( { - \cos w} \right)}_v - 2\int {\underbrace {\left( { - \cos w} \right)}_v} \underbrace {dw}_{du} \cr & = - 2w\cos w + 2\int {\cos w} dw \cr & = - 2w\cos w + 2\sin w + C \cr & {\text{Write in terms of }}x,{\text{ substitute }}\sqrt x {\text{ for }}w \cr & = - 2\sqrt x \cos \sqrt x + 2\sin \sqrt x + C \cr} $$
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