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 - Section 6.3 - Complex Rational Expressions - Exercise Set - Page 436: 31

Answer

$\frac{2b+a}{b-2a}$.

Work Step by Step

The given expression is $=\frac{\frac{2}{a^2}-\frac{1}{ab}-\frac{1}{b^2}}{\frac{1}{a^2}-\frac{3}{ab}+\frac{2}{b^2}}$ Multiply the numerator and the denominator by $a^2b^2$. $=\frac{a^2b^2}{a^2b^2}\cdot \frac{\frac{2}{a^2}-\frac{1}{ab}-\frac{1}{b^2}}{\frac{1}{a^2}-\frac{3}{ab}+\frac{2}{b^2}}$ Use the distributive property. $=\frac{a^2b^2\cdot \frac{2}{a^2}-a^2b^2\cdot\frac{1}{ab}-a^2b^2\cdot\frac{1}{b^2}}{a^2b^2\cdot\frac{1}{a^2}-a^2b^2\cdot\frac{3}{ab}+a^2b^2\cdot\frac{2}{b^2}}$ Simplify. $=\frac{2b^2-ab-a^2}{b^2-3ab+2a^2}$. Factor the fraction. Numerator $2b^2-ab-a^2$. $=2b^2-2ab+ab-a^2$ $=(2b^2-2ab)+(ab-a^2)$ $=2b(b-a)+a(b-a)$ $=(b-a)(2b+a)$ Denominator $b^2-3ab+2a^2$. $=b^2-3ab+2a^2$ $=b^2-2ab-ab+2a^2$ $=(b^2-2ab)+(-ab+2a^2)$ $=b(b-2a)-a(b-2a)$ $=(b-2a)(b-a)$ Plug all factors into the fraction. $=\frac{(b-a)(2b+a)}{(b-2a)(b-a)}$. Cancel common terms. $=\frac{2b+a}{b-2a}$.
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