若3x+5y+z=0,3x+y-7z=0则x+y-z的值等于 ( )
若2x+5y+4z=0,3x+y-7z=0,则x+y-z的值等于( )
4x-3y-6z=0,x+2y-7z=0是一个方程组,那么x-y+z/x+y+z的值等于
若{x+3y+10z=0 则 (x+y-z)/(x-y+z)
已知实数x,y,z满足:3x-y-3z=0和x-6y+6z=0(z≠0),则代数式x+y+z/x-y+z的值等于
已知x+4y+3z=3x-2y-5z=0,求x+2y-z/2x-3y+7z的值
已知x,y,z 大于0,x+y+z=2,求证 xz/y(y+z)+zy/x(x+y)+yx/z(z+x)大于等于2/3
如果x/2=y/7=z/5,x,y,z都不等于0,则(x+y+z)/(3x-y)等于多少?
若2x+5y-4z=0,3x+9y-7z=0,则x+y-z的值为
若x/2=y/3=z/4不等于0,求x+y+z/x+y-z的值
若xy-z不等于0,且(y+x)/x=(z+x)/y=(y+x)/z,求[(y+z)(z+x)(x+y)]/xyz的值?
2x+5y+4z=0,3x+y-7z=0,则x+y-z=?
方程组{4x-3y-3z=0,x-3y+z=0,(x.y.z不等于0),求x/z和y/z的值?