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: 30

Answer

$\dfrac{3x^2-4x+4}{(x-1)^2}$

Work Step by Step

Factor $x^2-2x+1$ using the special formula $a^2-2ab+b^2=(a-b)^2$ to obtain: $x^2-2x+1=(x-1)^2$ Substitute back the factors into the given expression. $=\dfrac{3x}{x-1}-\dfrac{x-4}{(x-1)^2}$ The LCD is $(x-1)^2$. Make the expressions similar by multiplying $x-1$ to both the numerator and denominator of the first expresison to obtain: $=\dfrac{3x}{x-1}\cdot \dfrac{x-1}{x-1}-\dfrac{x-4}{(x-1)^2}$ $=\dfrac{3x(x-1)}{(x-1)^2}-\dfrac{x-4}{(x-1)^2}$ Subtract the numerators and retain the denominator to obtain: $=\dfrac{3x(x-1)-(x-4)}{(x-1)^2}$ Use the distributive property. $=\dfrac{3x^2-3x-x+4}{(x-1)^2}$ $=\dfrac{3x^2-4x+4}{(x-1)^2}$ The numerator can no onger be factored. Hence, the lowest term is: $\dfrac{3x^2-4x+4}{(x-1)^2}$
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