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 369: 88

Answer

$x\in\{1, 10^{-\sqrt{3}}, 10^{\sqrt{3}}\}$

Work Step by Step

Let $t=\log x$ The equation becomes $t^{3}=3t$ $t^{3}-3t=0$ $t(t^{2}-3)=0$ ...the parentheses can be factored as a difference of squares... $t(t-\sqrt{3})(t+\sqrt{3})=0$ Solutions: $\left[\begin{array}{lll} t=0 & t=-\sqrt{3} & t=\sqrt{3}\\ \log x=0 & \log x=-\sqrt{3} & \log x=\sqrt{3}\\ x=1 & x=10^{-\sqrt{3}} & x=10^{\sqrt{3}} \end{array}\right]$ $x\in\{1, 10^{-\sqrt{3}}, 10^{\sqrt{3}}\}$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.