Calculus (3rd Edition)

Published by W. H. Freeman
ISBN 10: 1464125260
ISBN 13: 978-1-46412-526-3

Chapter 7 - Exponential Functions - Chapter Review Exercises - Page 388: 116

Answer

$$\frac{1}{2}$$

Work Step by Step

Since \begin{align*} \lim _{x \rightarrow 0}\left(\frac{e^{x}}{e^{x}-1}-\frac{1}{x}\right)&=\lim _{x \rightarrow 0}\left(\frac{xe^{x}-e^{x}+1}{x(e^{x}-1)} \right)\\ &=\frac{0}{0} \end{align*} Then by using L’Hôpital’s Rule \begin{align*} \lim _{x \rightarrow 0}\left(\frac{e^{x}}{e^{x}-1}-\frac{1}{x}\right)&=\lim _{x \rightarrow 0}\left(\frac{xe^{x}-e^{x}+1}{x(e^{x}-1)} \right)\\ &= \lim _{x \rightarrow 0}\left(\frac{xe^{x}+e^x-e^{x}}{xe^{x} +e^x-1 } \right)\\ &= \lim _{x \rightarrow 0}\left(\frac{xe^{x} +e^x}{xe^{x} +2e^x } \right)\\ &=\frac{1}{2} \end{align*}
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