Intermediate Algebra for College Students (7th Edition)

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

Chapter 6 - Review Exercises - Page 497: 24

Answer

$\frac{2x-8}{(x-3)(x-5)}$.

Work Step by Step

The given expression is $=\frac{x-3}{x^2-8x+15}+\frac{x+2}{x^2-x-6}$ Factor $x^2-8x+15$. Rewrite the middle term $-5x$ as $-5x-3x$ $=x^2-5x-3x+15$ Group terms. $=(x^2-5x)+(-3x+15)$ Factor each term. $=x(x-5)-3(x-5)$ Factor out $(x-5)$. $=(x-5)(x-3)$. Factor $x^2-x-6$. Rewrite the middle term $-5x$ as $-3x+2x$ $=x^2-3x+2x-6$ Group terms. $=(x^2-3x)+(2x-6)$ Factor each term. $=x(x-3)+2(x-3)$ Factor out $(x-3)$. $=(x-3)(x+2)$. Substitute all factors into the given expression. $=\frac{x-3}{(x-5)(x-3)}+\frac{x+2}{(x-3)(x+2)}$ Cancel common terms. $=\frac{1}{x-5}+\frac{1}{x-3}$ LCM $=$ greatest power of all the prime factors. LCM $=(x-3)(x-5)$ $=\frac{(x-3)}{(x-3)}\cdot \frac{1}{x-5}+\frac{(x-5)}{(x-5)}\cdot \frac{1}{x-3}$ Simplify. $=\frac{(x-3)}{(x-3)(x-5)}+\frac{(x-5)}{(x-5)(x-3)}$ Add both numerators because both denominators are equal. $=\frac{(x-3)+(x-5)}{(x-3)(x-5)}$ Simplify. $=\frac{x-3+x-5}{(x-3)(x-5)}$ $=\frac{2x-8}{(x-3)(x-5)}$.
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