$9\mathrm{.}2($a$)$ Write each system of equations as an augmented matrix, $($b$)$ find the solutions using Gaussian

elimination and back substitution, $($c$)$ then check the solution using MatLab commands: $\frac{\frac{?}{?}}{?}$ and inv.

$x_1+2x_2+3x_3=-1$

$4x_1+7x_2+14x_3=3$

$x_1+4x_2+4x_3=1$

Turn in the MatLab output.