Solve the following system using Gauss elimination with partial pivoting.
- $\left\{\begin{matrix} &2x_{1}+x_{2}+x_{3}=10\\ & 3x_{1}+2x_{2}+3x_{3}=18 \\ & 5x_{1}+4x_{2}+2x_{3}=9 \end{matrix}\right.$
- $\left\{\begin{matrix} &x_{1}+x_{2}-x_{3}+x_{4}=-5\\ & x_{1}+x_{2}+x_{3}+3x_{3}=-3\\ & x_{2}+x_{3}-x_{4}=6 \\ & -x_{1}+x_{2}+3x_{3}=11 \end{matrix}\right.$
