解y+2z=-2;3x+y-4z=1;2x-y+2x=8

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解y+2z=-2;3x+y-4z=1;2x-y+2x=8
解y+2z=-2;3x+y-4z=1;2x-y+2x=8

解y+2z=-2;3x+y-4z=1;2x-y+2x=8
y+2z=-2 (1)
3x+y-4z=1 (2)
2x-y+2z=8 (3)
(1)+(3)
2x+4z=6
x+2z=3 (4)
(2)+(3)
5x-2z=9 (5)
(4)+(5)
6x=12
x=2
z=(3-x)/2=1/2
y=2x+2z-8=-3

y+2z=-2 (1) 3x-4z=1 (2) 2x-y=8 (3) (1)+(3) 2x+2z=6 所以4x+4z=12 (4) (2)+(4) 7x=13 x=13/7 y=2x-8=-30/7 z=(-y-2)/2=8/7