{x-y-z=-1 {3x+5y +7z=11 {4x-y+2z=-1 求X,Y,
问题描述：
{x-y-z=-1 {3x+5y +7z=11 {4x-y+2z=-1 求X,Y,
答
x-y-z=-1(1)3x+5y+7z=11(2)4x-y+2z=-1(3)(1)*7 7x-7y-7z=-7(4)(2)+(4) 10x-2y=45x-y=2(1)*2 2x-2y-2z=-2(5)(3)+(5) 6x-3y=-32x-y=-1(6)5x-y=2(7)(7)-(6) 3x=3x=1y=2x+1=3z=x-y+1=1-3+1=-1x=1,y=3,z=-1