Big Ideas Math - Algebra 1, A Common Core Curriculum

Published by Big Ideas Learning LLC
ISBN 10: 978-1-60840-838-2
ISBN 13: 978-1-60840-838-2

Chapter 6 - Exponential Functions and Sequences - 6.5 - Solving Exponential Equations - Exercises - Page 329: 14

Answer

$x=-4$

Work Step by Step

The given expression is $\Rightarrow (\frac{1}{4})^x=256$ Rewrite $\frac{1}{4}$ as $4^{-1}$ and $256=4^4$. $\Rightarrow (4^{-1})^x=4^4$ Use $(a^n)^m=a^{n\cdot m}$ $\Rightarrow 4^{-1\cdot x}=4^{4}$ Simplify. $\Rightarrow 4^{-x}=4^{4}$ Equate the exponents. $\Rightarrow -x=4$ Multiply each side by $-1$. $\Rightarrow -1(-4)=-1(4)$ Simplify. $\Rightarrow x=-4$ Check: $(x=-4)$ $\Rightarrow (\frac{1}{4})^{-4}=256$ $\Rightarrow 4^{4}=256$ $\Rightarrow 256=256$ True. Hence, the solution is $x=-4$.
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