Calculus: Early Transcendentals 8th Edition

Published by Cengage Learning
ISBN 10: 1285741552
ISBN 13: 978-1-28574-155-0

Chapter 2 - Review - True-False Quiz - Page 166: 1


The mentioned statement is false.

Work Step by Step

$\lim\limits_{x \to 4}\Big(\frac{2x}{x-4}-\frac{8}{x-4}\Big)=\lim\limits_{x \to 4}\frac{2x}{x-4}-\lim\limits_{x \to 4}\frac{8}{x-4}$ We see that as $x\to 4$, $2x\to8$ and $(x-4)\to0$ So, $(\frac{2x}{x-4})\to+\infty$ and $(\frac{8}{x-4})\to+\infty$ Which means, both $\lim\limits_{x \to 4}\frac{2x}{x-4}$ and $\lim\limits_{x \to 4}\frac{8}{x-4}$ do not exist. However, the difference law $$\lim\limits_{x \to a}[f(x)-g(x)]=\lim\limits_{x \to a}f(x)-\lim\limits_{x \to a}g(x)$$can only be applied on the assumption that both $\lim\limits_{x \to a} f(x)$ and $\lim\limits_{x \to a}g(x)$ exist. Therefore, the mentioned statement is false.
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