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: 51

Answer

$\{7\}$.

Work Step by Step

First we will find the Least Common Denominator (LCD) of all denominators and use it to clear fractions. Factor $x^2-25$. Use the algebraic identity $a^2-b^2=(a+b)(a-b)$. $=(x+5)(x-5)$ Substitute the factor into the equation. $\frac{1}{x-5}-\frac{3}{x+5}=\frac{6}{(x+5)(x-5)}$ Multiply the equation by the LCD $(x+5)(x-5)$. $(x+5)(x-5)\left ( \frac{1}{x-5}-\frac{3}{x+5}\right )=(x+5)(x-5)\left (\frac{6}{(x+5)(x-5)}\right )$ Use the distributive property. $(x+5)(x-5)\cdot \frac{1}{x-5}-(x+5)(x-5)\cdot \frac{3}{x+5}=(x+5)(x-5)\cdot \frac{6}{(x+5)(x-5)}$ Simplify. $x+5-3(x-5)=6$ $x+5-3x+15=6$ $-2x+20=6$ Add $-20$ to both sides. $-2x+20-20=6-20$ Simplify. $-2x=-14$ Divide both sides $-2$. $\frac{-2x}{-2}=\frac{-14}{-2}$ Simplify. $x=7$. The solution set is $\{7\}$. Note: Check if the solution is correct. The given equation is defined for all real values of $x$ except the zeros of the denominators, which are $-5$ and $5$. Since $x=7$ is not a zero of a denominator, the solution is correct.
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