Calculus: Early Transcendentals 9th Edition

Published by Cengage Learning
ISBN 10: 1337613924
ISBN 13: 978-1-33761-392-7

Chapter 1 - Review - Exercises - Page 69: 36

Answer

$x=\frac{5}{e^3-1}$ or $x\approx 0.262$

Work Step by Step

$\ln x-1=\ln (5+x)-4$ (Move $-1$ and $\ln (5+x)$ and change their signs) $\ln x -\ln (5+x)=1-4$ (Use the property $\ln \frac{a}{b}=\ln a-\ln b$) $\ln \frac{x}{5+x}=-3$ (Take the exponent) $\frac{x}{5+x}=e^{-3}$ $\frac{x}{5+x}=\frac{1}{e^3}$ (Cross multiply) $e^3 x=5+x$ (Move $x$ and change the sign) $e^3x-x=5$ (Factor out $x$) $(e^3-1)x=5$ (Divide by $e^3-1$) $x=\frac{5}{e^3-1}$ $x=0.26197....$ $x\approx 0.262$ Thus, $x=\frac{5}{e^3-1}$ or $x\approx 0.262$.
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