{3x-2y+2z=10 ,x-5y+2z=13 ,7x+y-2z=-9 解3元1次方程

3x-2y+2z=10 ........................1
x-5y+2z=13 ......................2
7x+y-2z=-9 .....................3
1式+3式得
10x-y=1...................4
2式+3式得
8x-4y=4
2x-y=1...................5
4式-5式得
8x=0
x=0................6
将6式代入4式得
10*0-y=1
y=-1...................7
将6式，7式代入1式得
3*0-2*(-1)+2z=10
2+2z=10
2z=8
z=4
所以x=0,y=-1,z=4

3x-2y+2z=10.(1)x-5y+2z=13.(2)7x+y-2z=-9.(3)(1)+(3)得10x-y=1.(4)(2)+(3)得8x-4y=4即2x-y=1.(5)(4)-(5)得8x=0x=0代入(5)得-y=1y=-1把x=0,y=-1代入(1)得2+2z=10z=4解得x=0y=-1z=4