Precalculus (10th Edition)

Published by Pearson
ISBN 10: 0-32197-907-9
ISBN 13: 978-0-32197-907-0

Appendix A - Review - A.5 Rational Expressions - A.5 Assess Your Understanding - Page A41: 25

Answer

$\dfrac{2(x^2-2)}{x(x+2)(x-2)}$

Work Step by Step

The LCD is $x(x^2-4)$. Make the expressions similar by multiplying $x$ to both the numerator and denominator of the first expression multiplying $x^2-4$ to both the numerator and denominator of the second expression to obtain: $=\dfrac{x}{x^2-4}\cdot \dfrac{x}{x}+\dfrac{1}{x} \cdot\dfrac{x^2-4}{x^2-4}$ $=\dfrac{x^2}{x(x^2-4)}+\dfrac{x^2-4}{x(x^2-4)}$ Add the numerators and retain the denominator to obtain: $=\dfrac{x^2+x^2-4}{x(x^2-4)}$ $=\dfrac{2x^2-4}{x(x^2-2^2)}$ Factor each polynomial completely. Use special formula $a^2-b^2=(a+b)(a-b)$ to obtain: $=\dfrac{2(x^2-2)}{x(x+2)(x-2)}$
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