Precalculus: Mathematics for Calculus, 7th Edition

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

Chapter 4 - Review - Exercises: 58

Answer

$x=7$

Work Step by Step

$5^{4-x}=\dfrac{1}{125}$ Rewrite $125$ as $5^{3}$: $5^{4-x}=\dfrac{1}{5^{3}}$ Take $5^{3}$ to the numerator by changing the sign of its exponent: $5^{4-x}=5^{-3}$ If $5^{4-x}=5^{-3}$, then $4-x=-3$ $4-x=-3$ Solve for $x$: $-x=-3-4$ $-x=-7$ $x=7$
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