x+y=z (1)
2x+3y=1 (2)
3x+2y=z-1 (3)
(3)-(1)
2x+y=-1 (4)
(2)-(4)
2y=2
y=1
代入(4)
2x+1=-2
x=-1
代入(1)
z=x+y=0
所以x=-1,y=1,z=0