Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 9 - Section 9.5 - Exponential and Logarithmic Equations - Exercise Set - Page 727: 88

Answer

The solution set is $\{4\}$.

Work Step by Step

The given equation is $\log (x+3) + \log (x-2) = \log 14$ Use product rule. $\log (x+3)(x-2) = \log 14$ $ (x+3)(x-2) = 14$ Use the distributive property. $x^2+3x-2x-6=14$ Subtract $14$ from both sides. $x^2+x-6-14=14-14$ Simplify. $x^2+x-20=0$ Factor. $x^2+5x-4x-20=0$ $x(x+5)-4(x+5)=0$ $(x+5)(x-4)=0$ Set both factors equal to zero. $x+5=0$ or $x-4=0$ Isolate $x$. $x=-5$ or $x=4$. $-5$ does not exist in the logarithmic function domain. Hence, the solution is $x=4$.
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