Precalculus (10th Edition)

Published by Pearson
ISBN 10: 0-32197-907-9
ISBN 13: 978-0-32197-907-0

Chapter 5 - Exponential and Logarithmic Functions - 5.6 Logarithmic and Exponential Equations - 5.6 Assess Your Understanding - Page 311: 42



Work Step by Step

$5^{-x}=25\\ 5^{-x}=5^2$ We know that if $a^b=a^c$ and $a\ne0,1,-1$, then $b=c.$ Hence, $5^{-x}=5^2\longrightarrow -x=2$ Multiply both sides by $-1$ oto obtain: $-x(-1)=2(-1)\\ x=-2$.
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