4. Solve system by using Gaussian method/ apply elementary row operations/
B. x+3y+z=10
X-2y-z=-6
2x+y+2z=10
1 3 1 10
1 -2 -1 -6
2 1 2 10
1 3 1 10
0 -5 -2 -16
0 -5 4 2
5 0 1 2
0 -5 -2 -16
0 0 2 6
10 0 0 10
0 -5 0 -10
0 0 2 6
now divide each row to simplify
1 0 0 1
0 1 0 2
0 0 1 3