Calculus 8th Edition

Published by Cengage
ISBN 10: 1285740629
ISBN 13: 978-1-28574-062-1

Chapter 5 - Applications of Integration - Review - Exercises - Page 393: 6

Answer

$-\frac{2}{3}(2 \sqrt{2}-5)$

Work Step by Step

The area between two curves $y=f(x)$ and $y=g(x)$ between $x=a$ and $x=b$ is given by the formula: $$A=\int_a^b |f(x)-g(x)|dx.\quad\quad\quad(1)$$ Given $$f(x)=\sqrt{x}, \quad g(x)=x^2, \quad x=2$$ find the intersection points \begin{aligned} x^2&=\sqrt{x}\\ x^4&=x\\ x^4-x&=0\\ x(x^3-1)&=0 \end{aligned} Then $$x=0,\ \ x=1 $$ Since \begin{aligned} \sqrt{x}\geq x^2& \ \ \ \ 0\leq x\leq 1 \\ x^2 \geq \sqrt{x}\& \ \ \ \ 1\leq x\leq 2 \end{aligned} then use $(1)$: \begin{aligned} \text{Area} & = \int_0^1\left(\sqrt{x}-x^2\right) d x+\int_1^2\left(-\sqrt{x}+x^2\right) d x\\ &=\left(\frac{2}{3} x^{3/2} -\frac{1}{3}x^3\right) \bigg|_0^1 +\left(\frac{-2}{3} x^{3/2} +\frac{1}{3}x^3\right)\bigg|_1^2\\ &=-\frac{2}{3}(2 \sqrt{2}-5) \end{aligned}
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