## Algebra and Trigonometry 10th Edition

$\begin{bmatrix} -1 & 1 & |4\\ 2 & -4 & |-34\\ \end{bmatrix}$ ~ $\begin{bmatrix} -1 & 1 & |4\\ 1 & -2 & |-17\\ \end{bmatrix}$ ~ $\begin{bmatrix} -1 & 1 & |4\\ 0 & -1 & |-13\\ \end{bmatrix}$ Back-Substitution: -y = -13 y = 13 -x + 13 = 4 x = 9 x = 9 y = 13