Question

{x-y=5
{2x+y=1
solve by using a matrix equation

Answer 1

x-y=5
2x+y=1
----------
3x =6
x=6/3
x=2

Answer 2

\[\left[\begin{matrix}1 & -1 \\ 2 & 1\end{matrix}\right]\overrightarrow{x}=\left(\begin{matrix}5 \\ 1\end{matrix}\right)\]solve with Gaussian elimination, Cramer's rule, or whatever you wish.