Finite Math and Applied Calculus (6th Edition)

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

Chapter 10 - Section 10.3 - Limits and Continuity: Algebraic Viewpoint - Exercises - Page 719: 48

Answer

the limit diverges to +$\infty$.

Work Step by Step

1. f is a closed function. We know by Th.10.1 that it is continuous, that is, L= $\displaystyle \lim_{x\rightarrow a}f(x)$ = $f(a)$, for all a from the domain of f. 2. evaluating: $f(-1)$, (plugging $x=-1$) , we see that $x=-1$ is NOT in the domain of f. Factoring, we try to simplify f(x): $\displaystyle \frac{x(x+3)}{(x+2)(x+1)}$, but there is nothing to reduce. As $x\rightarrow 2,$ (we approach $2$ from either side), the numerator approaches -2, which is negative, for the denominator , evaluating it on either side... left: (test when x=-1.01), is negative, right: (test when x=-0.99) is also negative, so the denominator is negative regardless of the side we choose to approach -1. The limit takes the determinate form $\displaystyle \frac{k}{0^{\pm}}=\pm\infty $, and (negative/negative = positive) the limit diverges to +$\infty$.
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