Precalculus (10th Edition)

Published by Pearson
ISBN 10: 0-32197-907-9
ISBN 13: 978-0-32197-907-0

Appendix A - Review - A.6 Solving Equations - A.6 Assess Your Understanding - Page A51: 80

Answer

$\{-\frac{5}{2},1\}$

Work Step by Step

Multiply both sides by the LCD $(x+4)(x-2)$. $(x+4)(x-2)\left (\frac{5}{x+4} \right )= (x+4)(x-2)\left (4+\frac{3}{x-2}\right )$ Use distributive property. $(x+4)(x-2)\left (\frac{5}{x+4} \right )= (x+4)(x-2)\left (4\right )+ (x+4)(x-2)\left (\frac{3}{x-2}\right )$ Cancel the common factors. $\require{cancel} \begin{align*} \cancel{(x+4)}(x-2)\left (\frac{5}{\cancel{x+4}} \right )&= (x+4)(x-2)\left (4\right )+ (x+4)\cancel{(x-2)}\left (\frac{3}{\cancel{x-2}}\right )\\ \\5(x-2)&=4(x+4)(x-2) +3(x+4) \end{align*}$ Use distributive property and FOIL method. $5x-10=4(x^2-2x+4x-8) +3x+12$ $5x-10=4(x^2+2x-8) +3x+12$ $5x-10=4x^2+8x-32 +3x+12$ Simplify by combining like terms. $5x-10=4x^2+11x-20$ Add $-5x+10$ to both sides. $5x-10-5x+10=4x^2+11x-20-5x+10$ Simplify. $0=4x^2+6x-10$ Divide the equation by $2$. $0=2x^2+3x-5$ Rewrite $3x$ as $5x-2x$. $0=2x^2+5x-2x-5$ Group the terms. $0=(2x^2+5x)+(-2x-5)$ Factor out the GCF in each group. $0=x(2x+5)-1(2x+5)$ Factor out $(2x+5)$. $0=(2x+5)(x-1)$ Use Zero-Product Property. $2x+5=0\quad $ or $\quad x-1 =0$ Solve for $x$. $x=-\frac{5}{2}\quad $ or $\quad x =1$ Hence, the solution set of the given equation is $\{-\frac{5}{2},1\}$.
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