Calculus with Applications (10th Edition)

Published by Pearson
ISBN 10: 0321749006
ISBN 13: 978-0-32174-900-0

Chapter 3 - The Derivative - 3.2 Continuity - 3.2 Exercises - Page 147: 9

Answer

$$ f(x)=\frac{x^{2}-4}{x-2} $$ There is a discontinuity when $x=2$. So $$ \lim _{x \rightarrow 2} f(x)=2+2=4. $$

Work Step by Step

$$ f(x)=\frac{x^{2}-4}{x-2} $$ This rational function is discontinuous wherever the denominator is zero. There is a discontinuity when $x=2$. Since for $x \neq 2$ $$ \begin{split} f(x)&=\frac{x^{2}-4}{x-2} \\ &=\frac{(x-2)(x+2)}{(x-2)} \\ &=(x+2) \end{split} $$ So $$ \lim _{x \rightarrow 2} f(x)=2+2=4. $$
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