Answer
$5$
Work Step by Step
1. $log(x)+log(x+15)=2 \Longrightarrow log(x^2+15x)=2 \Longrightarrow x^2+15x=10^2 \Longrightarrow x^2+15x-100=0 \Longrightarrow (x+20)(x-5)=0 \Longrightarrow x=-20, 5$.
2. Check only $x=5$ fits.
Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)
by Sullivan III, Michael
Published by
Pearson
ISBN 10:
0-32193-104-1
ISBN 13:
978-0-32193-104-7
Chapter 4 - Exponential and Logarithmic Functions - Section 4.6 Logarithmic and Exponential Equations - 4.6 Assess Your Understanding - Page 337: 17
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