②-③ 3y-2z=12
①-②*2 -3y-z=-9 , -3z=3 ,z=-1
把z=-1带入① 和③
① 2x+y=1
③ x-y=-5
得, 3x=-4,x=-4/3
y=x+5=11/3
①2x+y-z=2 ②x+2y=5 ③x-y+2z=-7
2个回答
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