Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

Published by Pearson
ISBN 10: 0-32184-874-8
ISBN 13: 978-0-32184-874-1

Chapter 1-12 - Cumulative Review - Page 846: 8

Answer

$\frac{9}{2}$

Work Step by Step

The value of x is calculated as follows. $\begin{align} & \frac{7}{{{x}^{2}}-5x}-\frac{2}{x-5}=\frac{4}{x} \\ & \frac{7-2x}{x\left( x-5 \right)}=\frac{4}{x} \\ & 7-2x=4\left( x-5 \right) \\ & 7-2x=4x-20 \end{align}$ $\begin{align} & 4x+2x=7+20 \\ & 6x=27 \\ & x=\frac{27}{6} \\ & =\frac{9}{2} \end{align}$ Check: Substitute $\frac{9}{2}$ for $x$ in the given equation. $\begin{align} & \frac{7}{{{\left( \frac{9}{2} \right)}^{2}}-5\left( \frac{9}{2} \right)}-\frac{2}{\left( \frac{9}{2} \right)-5}=\frac{4}{\left( \frac{9}{2} \right)} \\ & \frac{7}{\left( \frac{81}{4}-\frac{45}{2} \right)}-\frac{2}{\left( \frac{9-10}{2} \right)}=\frac{8}{9} \\ & \frac{7}{\left( \frac{81-90}{4} \right)}-\frac{2}{\left( \frac{9-10}{2} \right)}=\frac{8}{9} \\ \end{align}$ Simplify further, $\begin{align} \frac{28}{-9}-\frac{4}{-1}\overset{?}{\mathop{=}}\,\frac{8}{9} & \\ \frac{28-36}{-9}\overset{?}{\mathop{=}}\,\frac{8}{9} & \\ \frac{-8}{-9}\overset{?}{\mathop{=}}\,\frac{8}{9} & \\ \frac{8}{9}\overset{?}{\mathop{=}}\,\frac{8}{9} & \\ \end{align}$
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