Find a general solution of the system, and use that solution to find a general solution of the associated homogeneous system and a particular solution of the given system.
$$\left[\begin{array}{cccc}
9 & -3 & 5 & 6 \\
6 & -2 & 3 & 1 \\
3 & -1 & 3 & 14
\end{array}\right]\left[\begin{array}{c}
x_{1} \\
x_{2} \\
x_{3} \\
x_{4}
\end{array}\right]=\left[\begin{array}{r}
4 \\
5 \\
-8
\end{array}\right]$$