x+y+z=4
2x-y+z=3
3x-2y-3z=-5
x =1,y= 1,z = 2
2x-3y+4z=11
3x+y-2z=3
z=x+y
x=2,y= -1,z =1x+y+z=41 2x-y+z=3 23x-2y-3z=-5 3(1)+(2)消去y2（2）-（3）也消去y然后再消去x或zx =1, y= 1, z = 22x-3y+4z=11 3x+y-2z=3 z=x+y把z=x+y替换前2个等式，再消去x或yx=2, y= -1, z =1