x+y-z=0(1)
x+2y-z=3(2)
2x-3y+2z=5(3)
(2)-(1)
y=3
化简
x-z=-2(4)
x+z=7(5)
(4)+(5)
2x=5
x=5/2
z=9/2
y/3-x+1/6=3
2(x-y/2)=3(x+y/18)
化简
2y-6x=17(1)
x=-7y/6(2)
(2)代入（1）
9y=17
y=17/9
x=-119/54