Calculus: Early Transcendentals 8th Edition

Published by Cengage Learning
ISBN 10: 1285741552
ISBN 13: 978-1-28574-155-0

Chapter 16 - Review - Exercises - Page 1149: 2

Answer

$\int_Cxds=\frac{5^{3/2}-1}{12}$

Work Step by Step

We can parameterize the parabola $y=x^{2}$ $C:x=t,y=t^{2}$ As we move from $(0,0)$ to $(1,1)$ , $t$ increases from $0$ to $1$. Therefore, we will integrate from 0 to 1. $ds=\sqrt {(\frac{dx}{dt})^{2}+(\frac{dy}{dt})^{2}}dt$ $ds=\sqrt {{1}^{2}+({2t})^{2}}dt$ $ds=\sqrt {4t^{2}+1}dt$ Now, $\int_Cxds=\int _{0}^{1}t\sqrt {4t^{2}+1}dt$ $=\frac{1}{8}\int _{0}^{1}8t\sqrt {4t^{2}+1}dt$ Substitute $4t^{2}+1=u$ and $8tdt=du$ Limits of integration will change from $\int _{0}^{1}$ to$\int _{1}^{5}$. $=\frac{1}{8}\int _{1}^{5}\sqrt {u}du$ $=\frac{1}{8}[\frac{2u^{3/2}}{3}] _{1}^{5}$ $=\frac{5^{3/2}-1}{12}$ Hence, $\int_Cxds=\frac{5^{3/2}-1}{12}$
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