｛x+y-2z=3 3x-7y+5z=5 2x+2y-3z=5

x/2=y/3=z/5 x+3y-z/x-3y+z {x+y+z=1;x+3y+7z=-1;z+5y+8z=-2 2x+5y+4z=0,3x+y-7z=0,则x+y-z=? 2x+5y+4z=6,3x+y-7z=-4,x+y-z=? 5x+3y+2z=2011 4x+6y+7z=2012 求x+y+z 已知2x+5y+4z=6 3x+y-7z=-4求x+y-z 已知x+4y+3z=3x-2y-5z=0,求x+2y-z/2x-3y+7z的值 x-y-z=-1 3x+5y+7z=11 4x-y+2z=-1 分别求出x=?y=?z=? 试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y) {5x-3y+z=2{5x+2y-4z=3{-5x+y-z=2 {x-y-z=-1{3x+5y+7z{4x-y+2x=- 2x+3y-z=11 2x+y-5z=8 -2+7y+z=19 已知x:y:z=4:5:7,求:(1)2x+3y+z/5z; (2)x+y/y+z.