Answer
Solution set = $\{(5.2)\}$
Work Step by Step
$D= $ determinant of the coefficient matrix
$=\left|\begin{array}{ll}
1 & 1\\
1 & -1
\end{array}\right|=1(-1)-1(1)=-2$
$D_{x}=$ in D, replace the x column with the constants column
$= \left|\begin{array}{ll}
7 & 1\\
3 & -1
\end{array}\right|=7(-1)-1(3)=-10$
$D_{y}=$ in D, replace the x column with the constants column
$=\left|\begin{array}{ll}
1 & 7\\
1 & 3
\end{array}\right|=3-7=-4$
$x=\displaystyle \frac{D_{x}}{D}=\frac{-10}{-2}=5$
$y=\displaystyle \frac{D_{y}}{D}=\frac{-4}{-2}=2$
Solution set = $\{(5.2)\}$
