Precalculus (10th Edition)

$\left[\begin{array}{rr|r} 9 & -1 & 0 \\ 3 & -1 & 4 \\ \end{array} \right]$
I modify the original equations in the form such that the constant "goes" onto the other side of the equality. $3x-y-4=0\\3x-y=4$ We know that $\left\{ \begin{array}{c} a_1x+b_1y=c_1 \\ a_2x+b_2y=c_2 \\ \end{array} \right.$ becomes $\left[\begin{array}{rr|r} a_1 & b_1 & c_1 \\ a_2 & b_2 & c_2 \\ \end{array} \right]$ Hence here the augmented matrix is: $\left[\begin{array}{rr|r} 9 & -1 & 0 \\ 3 & -1 & 4 \\ \end{array} \right]$