Thomas' Calculus 13th Edition

Published by Pearson
ISBN 10: 0-32187-896-5
ISBN 13: 978-0-32187-896-0

Chapter 3: Derivatives - Section 3.6 - The Chain Rule - Exercises 3.6 - Page 148: 26

Answer

$\frac{dy}{dx}$ = -$\frac{5}{x}$$sin^{-6}x$($cosx$) - ($\frac{1}{x^{2}}$)$sin^{-5}x$ + $x$$cos^{2}x$($sinx$) - $\frac{1}{3}$$cox^{3}x$

Work Step by Step

$y$ = $\frac{1}{x}$$sin^{-5}(x)$ - $\frac{x}{3}$$cos^{3}(x)$ $y$ = $\frac{1}{x}$$(sinx)^{5}$ - $\frac{x}{3}$$(cosx)^{3}$ differentiate with respect to x $\frac{dy}{dx}$ = $\frac{d}{dx}$[$\frac{1}{x}$$(sinx)^{-5}$] - $\frac{d}{dx}$[$\frac{x}{3}$$(cosx)^{3}$] use the product rule for each term $\frac{dy}{dx}$ = $\frac{1}{x}$$\frac{d}{dx}$[$(sinx)^{-5}$] + $(sinx)^{-5}$$\frac{d}{dx}$[$\frac{1}{x}$] - $\frac{x}{3}$$\frac{d}{dx}$[$(cosx)^{3}$] - $(cosx)^{3}$$\frac{d}{dx}$[$\frac{x}{3}$] solve derivative using the chain rule for $\frac{dy}{dx}$ = $\frac{1}{x}$$(-5)(sinx)^{-6}$$\frac{d}{dx}$($sinx$) + $(sinx)^{-5}$($-\frac{1}{x^{2}}$) - $\frac{x}{3}$$(3)(cosx)^{2}$$\frac{d}{dx}$[$(cosx)$] - $(cosx)^{3}$$\frac{1}{3}$ $\frac{dy}{dx}$ = $\frac{-5}{x}$$(sinx)^{-6}$($cosx$) - $(sinx)^{-5}$($\frac{1}{x^{2}}$) - $x$$(cosx)^{2}$(-$sinx$) - $(cosx)^{3}$$\frac{1}{3}$ $\frac{dy}{dx}$ = -$\frac{5}{x}$$sin^{-6}x$($cosx$) - ($\frac{1}{x^{2}}$)$sin^{-5}x$ + $x$$cos^{2}x$($sinx$) - $\frac{1}{3}$$cox^{3}x$ simplify $\frac{dy}{dx}$ = -$\frac{5}{x}$$sin^{-6}x$($cosx$) - ($\frac{1}{x^{2}}$)$sin^{-5}x$ + $x$$cos^{2}x$($sinx$) - $\frac{1}{3}$$cox^{3}x$
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