Algebra 2 Common Core

Published by Prentice Hall
ISBN 10: 0133186024
ISBN 13: 978-0-13318-602-4

Chapter 7 - Exponential and Logarithmic Functions - 7-5 Exponential and Logarithmic Equations - Practice and Problem-Solving Exercises - Page 473: 21

Answer

$y\approx 0.2720$

Work Step by Step

Recall the definition of a logarithm (pg. 451): $\log_{b}{x}=y$ iff $b^y=x$ Applying this definition to our equation (with $b=25, y=2x+1, x=144$), we get: $\log_{25}{144}=2x+1$ Next, recall the change of base formula (pg. 464): $\log_{b}{m}=\dfrac{\log_{c}{m}}{\log_{c}{b}}$ Applying this formula to our last equation, we get: $\log_{25}{144}=2x+1$ $\dfrac{\log_{10}{144}}{\log_{10}{25}}=2x+1$ $\dfrac{\log_{10}{144}}{\log_{10}{25}}-1=2x$ $\dfrac{1}{2}\frac{\log_{10}{144}}{\log_{10}{25}}-\frac{1}{2}=x$ $y\approx 0.2720$ We confirm that the answer works: $25^{2\cdot0.2720+1}=144$ $25^{1.544}=144$ $144=144$
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