Intermediate Algebra (12th Edition)

Published by Pearson
ISBN 10: 0321969359
ISBN 13: 978-0-32196-935-4

Chapter 8 - Review Exercises - Page 574: 19

Answer

$\left\{-\dfrac{5}{2},3\right\}$

Work Step by Step

Multiplying both sides by the $LCD= x ,$ the given equation, $ \dfrac{15}{x}=2x-1 $, is equivalent to \begin{align*} x\left(\dfrac{15}{x}\right)&=(2x-1)x \\\\ 1(15)&=(2x)x-1(x) \\ 15&=2x^2-x \\ 0&=2x^2-x-15 \\ 2x^2-x-15&=0 .\end{align*} Using factoring of trinomials, the equation above is equivalent to \begin{align*} (x-3)(2x+5)&=0 .\end{align*} Equating each factor to zero (Zero Product Property) and solving for the variable, then \begin{array}{l|r} x-3=0 & 2x+5=0 \\ x=3 & 2x=-5 \\ & x=-\dfrac{5}{2} .\end{array} Hence, the solution set of the equation $ \dfrac{15}{x}=2x-1 $ is $ \left\{-\dfrac{5}{2},3\right\} $.
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