x-y+2z=-1,2x+y-z=-1,3x-2y-2z=-9

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x-y+2z=-1,2x+y-z=-1,3x-2y-2z=-9
x-y+2z=-1,2x+y-z=-1,3x-2y-2z=-9

x-y+2z=-1,2x+y-z=-1,3x-2y-2z=-9
x-y+2z=-1 (1)
2x+y-z=-1 (2)
3x-2y-2z=-9 (3)
由(1)得y=x+2z+1,分别代入(2)、(3),得
3x+z=-2 (4)
x-6z=-7 (5)
(4)×6+(5)
19x=-19
x=-1
代入(4)
z=-3x-2=-3(-1)-2=1
y=x+2z+1=-1+2+1=2
x=-1 y=2 z=1