Finite Math and Applied Calculus (6th Edition)

Published by Brooks Cole
ISBN 10: 1133607705
ISBN 13: 978-1-13360-770-0

Chapter 11 - Section 11.3 - The Product and Quotient Rules - Exercises - Page 818: 72

Answer

$y=7x-3$

Work Step by Step

For x=1, the point on the graph is $(1, f(1))$. The slope of the tangent at x=1 is $m=f^{\prime}(1).$ The point-slope equation of the tangent line is $y-y_{1}=m(x-x_{1})$ $y-f(1)=f^{\prime}(1)(x-1)$ $f(1)=( 1+1)(1+1)=4$ For $f^{\prime}(x)$, use the product rule, $\displaystyle \frac{d}{dx}[f(x)g(x)]=f^{\prime}(x)g(x)+f(x)g^{\prime}(x)$. $=(x^{0.5}+1)^{\prime}(x^{2}+x)+(x^{0.5}+1)(x^{2}+x)^{\prime}$ $f^{\prime}(x)=(0.5x)(x^{2}+x)+(x^{0.5}+1)(2x+1)$ ... evaluate at x=1 ... $f^{\prime}(1)=0.5(1+1)+(1+1)(2+1)$ $=1+6=7$ An equation for the tangent line is $y-4=7(x-1)$ $y=7x-7+4$ $y=7x-3$
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