Intermediate Algebra (12th Edition)

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

Chapter 8 - Chapter R-8 - Cumulative Review Exercises - Page 579: 28

Answer

$-\dfrac{8}{x}$

Work Step by Step

The factored form of the given expression, $ \dfrac{3}{2-x}-\dfrac{5}{x}+\dfrac{6}{x^2-2x} ,$ is \begin{align*} & \dfrac{3}{2-x}-\dfrac{5}{x}+\dfrac{6}{x(x-2)} \\\\&= \dfrac{3}{-(-2+x)}-\dfrac{5}{x}+\dfrac{6}{x(x-2)} \\\\&= -\dfrac{3}{x-2}-\dfrac{5}{x}+\dfrac{6}{x(x-2)} .\end{align*} Changing each term to similar fractions by making the denominators equal to the $LCD= x(x-2) $, the expression above is equivalent to \begin{align*}\require{cancel} & -\dfrac{3}{x-2}\cdot\dfrac{x}{x}-\dfrac{5}{x}\cdot\dfrac{x-2}{x-2}+\dfrac{6}{x(x-2)} \\\\&= -\dfrac{3x}{x(x-2)}-\dfrac{5(x-2)}{x(x-2)}+\dfrac{6}{x(x-2)} \\\\&= \dfrac{-3x-5(x-2)+6}{x(x-2)} \\\\&= \dfrac{-3x-5x+10+6}{x(x-2)} \\\\&= \dfrac{-8x+16}{x(x-2)} \\\\&= \dfrac{-8(x-2)}{x(x-2)} \\\\&= \dfrac{-8\cancel{(x-2)}}{x\cancel{(x-2)}} \\\\&= \dfrac{-8}{x} \\\\&= -\dfrac{8}{x} .\end{align*} Hence, the expression $ \dfrac{3}{2-x}-\dfrac{5}{x}+\dfrac{6}{x^2-2x} $ simplifies to $ -\dfrac{8}{x} $.
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