[-2, 2, 1, 0]
[1, -2, 2, 0]
[-5, -4, -3, -56]
I und II tauschen
[1, -2, 2, 0]
[-2, 2, 1, 0]
[-5, -4, -3, -56]
II + 2*I ; III + 5*I
[1, -2, 2, 0]
[0, -2, 5, 0]
[0, -14, 7, -56]
III - 7*II
[1, -2, 2, 0]
[0, -2, 5, 0]
[0, 0, -28, -56]
-28*z = -56 --> z = 2
-2*y + 5*2 = 0 --> y = 5
x - 2*5 + 2*2 = 0 --> x = 6