已知x-2y+z=0,7x+4y-5z=0,则x:y:z=?急!
已知方程组4x-5y+2z=0 x+2y=3z 则x:y:z
已知,方程组:4x-3y-7z=0 x+2y=10z 则(x-y+z)÷(x+y+z)=——
已知x+4y+3z=3x-2y-5z=0,求x+2y-z/2x-3y+7z的值
2x+5y+4z=0,3x+y-7z=0,则x+y-z=?
1.已知x:y:z=4:5:7,求:(一)2x+3y+z/5z; (二)x+y/y+z 非常急,
已知{x-3y+2z=0 3x-3y-4z+0,则x:y:z=?
已知x+y-z/z=x-y+z/y=-x+y+z/x,且xyz不等于0,求分式[(x+y)(x+z)(y+z)]/xyz
已知:(x+y-z)/z=(x-y+z)/y+(y+z-x)/x,且xyz≠0,求代数式[(x+y)(y+z)(x+z)
已知3x-2y-5z=0,2x-5y+4z=0,且x,y,z均不为0,求3x*x+2y*y+5z*z/5x*x+y*y-
已知x+y-7z=0 x-2y+5z=0(xyz不等于0),求x+2y-z/y-2x+12z
已知x+2y-4z=0,3x-y-z=0,则3x+2y+z/x+2y+z=
已知方程组4x-y+3z=0 2x+y+6z=0且xyz不等于0,则x/y+y/z+z/x是多少