Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 7 - Cumulative Review Exercises - Page 579: 10

Answer

$\frac{5x-6}{(x-5)(x+3)}$.

Work Step by Step

The given expression is $=\frac{7x}{x^2-2x-15}-\frac{2}{x-5}$ Factor $x^2-2x-15$. Rewrite the middle term $-2x$ as $-5x+3x$. $\Rightarrow x^2-5x+3x-15$ Group the terms. $\Rightarrow (x^2-5x)+(3x-15)$ Factor each group. $\Rightarrow x(x-5)+3(x-5)$ Factor out $(x-5)$. $\Rightarrow (x-5)(x+3)$ Back substitute into the fraction. $=\frac{7x}{(x-5)(x+3)}-\frac{2}{x-5}$ The LCD is $(x-5)(x+3)$. Multiply the numerator and the denominator: $=\frac{7x}{(x-5)(x+3)}-\frac{2(x+3)}{(x-5)(x+3)}$ $=\frac{7x-2(x+3)}{(x-5)(x+3)}$ Use the distributive property. $=\frac{7x-2x-6}{(x-5)(x+3)}$ Simplify. $=\frac{5x-6}{(x-5)(x+3)}$.
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