College Algebra (11th Edition)

Published by Pearson
ISBN 10: 0321671791
ISBN 13: 978-0-32167-179-0

Chapter 4 - Section 4.5 - Exponential and Logarithmic Equations - 4.5 Exercises - Page 446: 30


$x=\ln5$ or $x=\ln3$

Work Step by Step

Let $u=e^x$ $e^{2x}-8^x+15=0$ $u^2-8u+15=0$ Factor. $(u-5)(u-3)=0$ Equate each factor to 0. $u=5$ or $u=3$ Since $e^x=u$ $e^x=5$ or $e^x=3$ $x=\ln5$ or $x=\ln3$
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