Answer:
The solution is x=0, y=0, z=1
Step-by-step explanation:
Step1: -row2 + row1; -row2 + row3
x + 2y - z = -1
x + y + z = 1
x - y - z = -1
1 2 -1 -1
1 1 1 1
1 -1 -1 -1
0 1 -2 -2
1 1 1 1
0 -2 -2 -2
Step 2: row3/-2
0 1 -2 -2
1 1 1 1
0 1 1 1
step 3: -row3 + row1
0 0 -3 -3
1 1 1 1
0 1 1 1
step 4: row1/-3
0 0 1 1
1 1 1 1
0 1 1 1
step 4: -row1 + row3; -row1 + row2
0 0 1 1
1 1 0 0
0 1 0 0
step 5: -row3 + row2
0 0 1 1
1 0 0 0
0 1 0 0
The reduced row echelon form is:
1 0 0 0
0 1 0 0
0 0 1 1