Precalculus (6th Edition) Blitzer

Published by Pearson
ISBN 10: 0-13446-914-3
ISBN 13: 978-0-13446-914-0

Chapter 3 - Section 3.4 - Exponential and Logarithmic Equations - Exercise Set - Page 489: 88

Answer

Solution set = $\{4\}.$

Work Step by Step

For the equation to be defined, logarithms must have positive arguments $\left[\begin{array}{llll} x+3 \gt 0, & and & x-2 \gt 0 & \\ x\gt-3 & & x\gt 2 & \end{array}\right]$ $ x \gt 2 \qquad (*)$ This is the condition eventual solutions must satisfy. $\log(x+3)+\log(x-2)=\log 14\qquad $... LHS: product rule $\log(x^{2}+x-6)=\log 14 \quad $ ... $\log $ is one-to-one $ x^{2}+x-6=14$ $ x^{2}+x-20=0$ Factor: +5 and -4 are factors of -20 whose sum is +1. $(x+5)(x-4)=0$ $ x=4 \qquad $ ... satisfies (*) $ x=-5 \quad $ ... does not satisfy (*) Thus, the solution set = $\{4\}.$
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.