Intermediate Algebra (6th Edition)

Published by Pearson
ISBN 10: 0321785045
ISBN 13: 978-0-32178-504-6

Chapter 8 - Section 8.3 - Solving Equations by Using Quadratic Methods - Exercise Set - Page 501: 9

Answer

$\left\{ \dfrac{3-\sqrt{57}}{4},\dfrac{3+\sqrt{57}}{4} \right\}$

Work Step by Step

Multiplying both sides of the given equation, $ \dfrac{3}{x}+\dfrac{4}{x+2}=2 ,$ by the $LCD= x(x+2) $, then, \begin{array}{l}\require{cancel} x(x+2)\left( \dfrac{3}{x}+\dfrac{4}{x+2} \right)=\left( 2\right)x(x+2) \\\\ (x+2)(3)+x(4)=2x^2+4x \\\\ 3x+6+4x=2x^2+4x \\\\ -2x^2+(3x+4x-4x)+6=0 \\\\ -2x^2+3x+6=0 .\end{array} Using $\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}$ (or the Quadratic Formula), the solutions of the quadratic equation, $ -2x^2+3x+6=0 ,$ are \begin{array}{l}\require{cancel} \dfrac{-(3)\pm\sqrt{(3)^2-4(-2)(6)}}{2(-2)} \\\\= \dfrac{-3\pm\sqrt{9+48}}{-4} \\\\= \dfrac{-3\pm\sqrt{57}}{-4} \\\\= \dfrac{3\pm\sqrt{57}}{4} .\end{array} Upon checking, both solutions satisfy the original equation. Hence, the solutions are $ \left\{ \dfrac{3-\sqrt{57}}{4},\dfrac{3+\sqrt{57}}{4} \right\} .$
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