Precalculus: Mathematics for Calculus, 7th Edition

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

Chapter 4 - Section 4.5 - Exponential and Logarithmic Functions - 4.5 Exercises - Page 368: 51

Answer

$x=4$ and $x=2$

Work Step by Step

$2\log x=\log2+\log(3x-4)$ Rewrite the left side of the equation by raising the argument of the $\log$ to the power of $2$: $\log x^{2}=\log2+\log(3x-4)$ Now, combine the logarithms on the right side as a product: $\log x^{2}=\log2(3x-4)$ $\log x^{2}=\log(6x-8)$ Since $\log$ is one to one, this equation becomes: $x^{2}=6x-8$ Take all terms to the left side: $x^{2}-6x+8=0$ Solve by factoring: $(x-4)(x-2)=0$ We get two solutions: $x=4$ and $x=2$
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