Answer
$x=-2$
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:
$-x(-1)=2(-1)\\
x=-2$.
Precalculus (10th Edition)
by Sullivan, Michael
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
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