x-2y+z=9 (1)2x+y+3z=10 (2)3x+2y-4z=-3 (3)(2)*2+(1)5x+7z=29 (4)(1)+(3)4x-3z=6 (5)(4)*4-(5)*543z=86z=2把z=2代入（5）4x-6=6x=3把x=3,z=2代入(2)6+y+6=10y=-2x=3,y=-2,z=2