Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 4 - Section 4.5 - Exponential and Logarithmic Functions - 4.5 Exercises - Page 368: 39

Answer

$x=\ln2\approx0.693147$ and $x=0$

Work Step by Step

$e^{2x}-3e^{x}+2=0$ Let $e^{x}=u$ and $e^{2x}=u^{2}$ and rewrite the equation: $u^{2}-3u+2=0$ Solve by factoring: $(u-2)(u-1)=0$ We get two solutions, which are: $u=2$ and $u=1$ Let's undo the initial substitution, knowing that $u=e^{x}$. The solutions become: $e^{x}=2$ and $e^{x}=1$ Solve for $x$ in both equations: $x=\ln2$ and $x=0$ Our two final solutions are: $x=\ln2\approx0.693147$ and $x=0$
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