解方程一;{x+y-z=6,x-3y+2z=1,3x+2y-z=-7.②{3x+4z=7,2x+3y+z=9,5x-9y+7=-6.

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解方程一;{x+y-z=6,x-3y+2z=1,3x+2y-z=-7.②{3x+4z=7,2x+3y+z=9,5x-9y+7=-6.解方程一;{x+y-z=6,x-3y+2z=1,3x+2y-z=-7

解方程一;{x+y-z=6,x-3y+2z=1,3x+2y-z=-7.②{3x+4z=7,2x+3y+z=9,5x-9y+7=-6.
解方程一;{x+y-z=6,x-3y+2z=1,3x+2y-z=-7.②{3x+4z=7,2x+3y+z=9,5x-9y+7=-6.

解方程一;{x+y-z=6,x-3y+2z=1,3x+2y-z=-7.②{3x+4z=7,2x+3y+z=9,5x-9y+7=-6.
x+y-z=6,①
x-3y+2z=1,②
3x+2y-z=-7 ③
①-②得 4y-3z=5 ④
①*3-③得 y-2z=25 ⑤
④-⑤*4得5z=-95
z=-19
代入⑤得y+38=25
y=-13
代入①得x-13+19=6
x=0
∴.
第二题方法类似,原题打字有误,请审核后仿照第一题.

解方程一
x+y-z=6……(1)
x-3y+2z=1……(2)
3x+2y-z=-7……(3)
(3)-(1)得:2x+y=-13(4)
(1)×2+(2)得:3x-y=13……(5)
(4)+(5)得x=0
y=-13
∴z=y-6=-19