3x+2y=1 (1)
2x-y+2z=-4 (2)
x+2y-z=3 (3)
(1)+(2)×2
4x+3y=2 (4)
(4)-(1)
x+y=1 (5)
(1)-(5)×2
3x+2y-2x-2y=1-2
x=-1
y=1-x=2
z=x+2y-3=0
即x=-1,y=2,z=0