4x-3y-z=16,2x+2y+3z=8,x+4y+5z=3
3个回答

4x-3y-z=16.(1)

2x+2y+3z=8.(2)

x+4y+5z=3 .(3)

(2)*2-(1):4x+4y+6z-(4x-3y-z)=16-16

7y+7z=0...(4)

(3)*4-(1):4x+16y+20z-(4x-3y-z)=12-16

19y+21z=-4.(5)

(4)*3-(5):21y+21z-(19y+21z)=0+4

2y=4

y=2

把y=2代入(4)

有z=-2

将y=2,z=-2代入(3)中,有

x+8-10=3

x=5

所以x=5,y=2,z=-2