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 A42: 44

Answer

$\dfrac{-2(x^2-5x-9)}{(x^2+9)^2}$

Work Step by Step

Use distributive property. $\dfrac{(x^2+9)\cdot 2-(2x-5)\cdot 2x}{(x^2+9)^2}\\ =\dfrac{2x^2+18-(4x^2-10x)}{(x^2+9)^2}\\ =\dfrac{2x^2+18-4x^2+10x}{(x^2+9)^2}$ Simplify by combining like terms. $=\dfrac{-2x^2+10x+18}{(x^2+9)^2}$ Factor the numerator by factoring out $-2$. $=\dfrac{-2(x^2-5x-9)}{(x^2+9)^2}$ The numerator can no longer be factored further. Hence, the lowest term is $\dfrac{-2(x^2-5x-9)}{(x^2+9)^2}$.
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