Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 4 - Section 4.4 - Linear Inequalities in Two Variables - Exercise Set - Page 297: 96

Answer

$\{(3,1)\}$.

Work Step by Step

The given system of equations is $3x-y=8$ $x-5y=-2$ The augmented matrix is $\Rightarrow \left[\begin{array}{cc|c} 3 & -1 & 8\\ 1 & -5 & -2 \end{array}\right]$ Perform $R_1\leftrightarrow R_2$. Swap the second and the first row. $\Rightarrow \left[\begin{array}{cc|c} 1 & -5 & -2\\ 3 & -1 & 8 \end{array}\right]$ Perform $R_2\rightarrow R_2-3\times R_1$. $\Rightarrow \left[\begin{array}{cc|c} 1 & -5 & -2\\ 3-3(1) & -1-3(-5) & 8-3(-2) \end{array}\right]$ Simplify. $\Rightarrow \left[\begin{array}{cc|c} 1 & -5 & -2\\ 0 & 14 & 14 \end{array}\right]$ Perform $R_2\rightarrow \frac{R_2}{14}$. $\Rightarrow \left[\begin{array}{cc|c} 1 & -5 & -2\\ 0/14 & 14/14 & 14/14 \end{array}\right]$ Simplify. $\Rightarrow \left[\begin{array}{cc|c} 1 & -5 & -2\\ 0 & 1 & 1 \end{array}\right]$ Perform $R_1\rightarrow R_1+5R_2$. $\Rightarrow \left[\begin{array}{cc|c} 1+5(0) & -5+5(1) & -2+5(1)\\ 0 & 1 & 1 \end{array}\right]$ Simplify. $\Rightarrow \left[\begin{array}{cc|c} 1 & 0 & 3\\ 0 & 1 & 1 \end{array}\right]$ Use back substitution to solve the linear system. $\Rightarrow x=3$ and $\Rightarrow y=1$. The solution set is $\{(x,y)\}=\{(3,1)\}$.
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