{3x-5y+2z=1 {4x+5y-z=5 {x-5y+3z=-2
3x-5y+2z=1 ①
4x+5y-z=5 ②
x-5y+3z=-2 ③
4*①-3*②得 -35y+11z=-11 ④
①-3*③得 10y-7z=7 ⑤
-2*④-7*⑤得 27z=-27 z=-1
代入z到④,得y=0
代入y和z到①,得x=1
因此 x=1 y=0 z=-1
o(∩_∩)o