Intermediate Algebra for College Students (7th Edition)

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

Chapter 3 - Test - Page 251: 15

Answer

$\{(4,-2)\}$.

Work Step by Step

The given system of equations is $\left\{\begin{matrix} 2x& +y &=&6\\ 3x& -2y &=&16 \end{matrix}\right.$ The augmented matrix is $\Rightarrow \left[\begin{array}{cc|c} 2& 1 & 6\\ 3 & -2 & 16 \end{array}\right]$ Perform $R_1\rightarrow R_1/2$. $\Rightarrow \left[\begin{array}{cc|c} 2/2& 1/2 & 6/2\\ 3 & -2 & 16 \end{array}\right]$ Simplify. $\Rightarrow \left[\begin{array}{cc|c} 1& 1/2 & 3\\ 3 & -2 & 16 \end{array}\right]$ Perform $R_2\rightarrow R_2-3R_1$. $\Rightarrow \left[\begin{array}{cc|c} 1& 1/2 & 3\\ 3-3(1) & -2-3(1/2) & 16-3(3) \end{array}\right]$ Simplify. $\Rightarrow \left[\begin{array}{cc|c} 1& 1/2 & 3\\ 0 & -7/2 & 7 \end{array}\right]$ Perform $R_2\rightarrow R_2(-2/7)$. $\Rightarrow \left[\begin{array}{cc|c} 1& 1/2 & 3\\ 0(-2/7) & -7/2(-2/7) & 7(-2/7) \end{array}\right]$ Simplify. $\Rightarrow \left[\begin{array}{cc|c} 1& 1/2 & 3\\ 0 & 1 & -2 \end{array}\right]$ Perform $R_1\rightarrow R_1-(1/2) R_2$. $\Rightarrow \left[\begin{array}{cc|c} 1-(1/2)(0)& 1/2-(1/2)(1) & 3-(1/2)(-2)\\ 0 & 1 & -2 \end{array}\right]$ Simplify. $\Rightarrow \left[\begin{array}{cc|c} 1& 0 & 4\\ 0 & 1 & -2 \end{array}\right]$ Use back substitution to solve the linear system. $\Rightarrow x=4$ and $\Rightarrow y=-2$. The solution set is $\{(x,y)\}=\{(4,-2)\}$.
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.