[tex]\begin{cases}-3x+y=-2\\x+y=-6\end{cases}\iff\begin{bmatrix}-3&1\\1&1\end{bmatrix}\begin{bmatrix}x\\y\end{bmatrix}=\begin{bmatrix}-2\\-6\end{bmatrix}[/tex]
[tex]\implies\begin{bmatrix}x\\y\end{bmatrix}=\begin{bmatrix}-3&1\\1&1\end{bmatrix}^{-1}\begin{bmatrix}-2\\-6\end{bmatrix}=\begin{bmatrix}-1\\-5\end{bmatrix}[/tex]
