Calculus 8th Edition

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

Chapter 4 - Integrals - 4.4 Indefinite Integrals and the Net Change Theorem - 4.4 Exercises - Page 337: 26

Answer

$2$

Work Step by Step

We can rewrite the terms in the integrand to remove the fractions, which can be easier to integrate. This would make our new integrand is $\int_1^2 (x^{-2} - 4x^{-3}dx) $ We can treat the $4$ as a constant and can multiply it by the integral of $x^{-3}$. Our integral would be $-x^{-1} - (4) \frac{(-x^{-2})}{{-2}} \Big|_1^2$ Before substituting our bounds of integration, we can simplify the expression as $-\frac{1}{x} - (4)(\frac{1}{2x^2}) $ $ = -\frac{1}{x} - \frac{2}{x^2}$ $= -\frac{x+2}{x^2}$ We now substitute $2$ and $1$ into $x$ and get $-\frac{(2) + 2}{(2)^2} - (- \frac {(1) + 2}{(1)^2})$ $ = -\frac{4}{4} + \frac{3}{1}$ $ = -1 + 3 = 2$
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