3x-y+7=0 (1)
y+4z-3=0 (2)
2x-2z+5=0 (3)
(1)+(2)
3x+4z+4=0 (4)
(3)×2+(4)
4x+3x+10+4=0
7x=-14
x=-2
代入(1),(3)
-6-y+7=0,y=1,
-4-2z+5=0,z=1/2
所以
x=-2,y=1,z=1