Finite Math and Applied Calculus (6th Edition)

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

Chapter 11 - Section 11.1 - Derivatives of Powers, Sums, and Constant Multiples - Exercises - Page 795: 78

Answer

L'Hospital's rule applies. limit = $-1$

Work Step by Step

Theorem 11.3 L'Hospital's Rule: If $f$ and $g$ are differentiable functions such that substituting $x=a$ in the expression $\displaystyle \frac{f(x)}{g(x)}$ gives the indeterminate form $\displaystyle \frac{0}{0}$ or $\displaystyle \frac{\infty}{\infty}$, then $\displaystyle \lim_{x\rightarrow a}\frac{f(x)}{g(x)}=\lim_{x\rightarrow a} \displaystyle \frac{f^{\prime}(x)}{\mathrm{g}^{\prime}(x)}$. That is, we can replace $f(x)$ and $g(x)$ with their derivatives and try again to take the limit. -------------------- When x approaches $-1$, the numerator approaches 0, the denominator approaches 0, $\displaystyle \frac{f(x)}{g(x)}$ gives the indeterminate form $\displaystyle \frac{0}{0}$, L'Hospital's rule applies. $\displaystyle \lim_{x\rightarrow-1}\frac{x^{2}+3x+2}{x^{2}+x}=\lim_{x\rightarrow-1} \displaystyle \frac{[x^{2}+3x+2]^{\prime}}{[x^{2}+x]^{\prime}}$ $=\displaystyle \lim_{x\rightarrow 1} \displaystyle \frac{2x+3}{2x+1}=$ . $=\displaystyle \frac{2(-1)+3}{2(-1)+1}=\frac{1}{-1}=-1$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.