Question

Use an augmented matrix to solve the system. What is the value of x and y?

x+y=5
3x-y=-1

Answer 1

\[\left[
\begin{array}{cc|c}
1&1&5\\3&-1&-1
\end{array}\right]
\]
That's the matrix, now use elimination on it :)

Answer 2

row reduction by elementary operations.