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: 54

Answer

$\{-23,2\}$.

Work Step by Step

Determine the Least Common Denominator ($LCD$) so that we clear the fractions. $LCD=4(x-1)(x+2)$. Multiply the given equation by $4(x-1)(x+2)$. $\Rightarrow 4(x-1)(x+2) \left (\frac{2}{x-1}\right )=4(x-1)(x+2)\left (\frac{1}{4}+\frac{7}{x+2}\right )$ Use distributive property and cancel common terms. $\Rightarrow 4(x-1)(x+2) \left (\frac{2}{x-1}\right )=4(x-1)(x+2)\left (\frac{1}{4}\right )+4(x-1)(x+2)\left (\frac{7}{x+2}\right )$ Cancel common factors. $\Rightarrow 8(x+2) =(x-1)(x+2)+28(x-1)$ Use the FOIL method and the distributive property. $\Rightarrow 8x+16 =x^2+2x-1x-2+28x-28$ Add like terms. $\Rightarrow 8x+16 =x^2+29x-30$ Add $-8x-16$ to both sides. $\Rightarrow 8x+16-8x-16 =x^2+29x-30-8x-16$ Simplify. $\Rightarrow 0=x^2+21x-46$ Rewrite the middle term as $21x$ as $23x-2x$. $\Rightarrow 0=x^2+23x-2x-46$ Group the terms. $\Rightarrow 0=(x^2+23x)+(-2x-46)$ Factor each group. $\Rightarrow 0=x(x+23)-2(x+23)$ Factor out $(x+23)$. $\Rightarrow 0=(x+23)(x-2)$ By using zero product rule set each factor equal to zero. $\Rightarrow x+23=0$ or $x-2=0$ Isolate $x$. $\Rightarrow x=-23$ or $x=2$ The solution set is $\{-23,2\}$. Note: The equation is defined for all real values of $x$ except the zeros of the denominators which are: $-2$ and $1$, therefore the solution set we found is correct.
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