MATH 168 / Write the system of equations corresponding to the augmented matrix using the variables \( x, y \), and \( z \). \[ \left[\begin{array}{rrr|r} 0 & -1 & -8 & -4 \\ 4 & -7 & -8 & 8 \\ -7 & 0 & 9 & -4 \e 2 answers