xy/x+y=1/27 yz/y+z=1/33 xz/x+z=1/30,求x,y,z,

解方程组：xy/(x+y)=1/27,yz/(y+z)=1/33,xz/(x+z)=1/30 证明 当x+y+z=1时,x/yz+y/xz+z/xy≥9 x+y+z=5,xy+xz+yz=1 ,求Z的最小值和最大值 已知xyz=1,求x/(xy+x+1)+y/(yz+y+1)+z/(xz+z+1)的值 已知,xyz=0,求x/(xy+x+1)+y/(yz+y+1)+z/(xz+z+1）值? 已知x+y+z=1,x²+y²+z²=2求xy+yz+xz的值 x-3=y-2=z-1,求x^2+y^2+z^2-xy-yz-xz的值 已知x+y+z=1,xy+yz+xz=0,求x^2+y^2+z^2的值. x+y+z=1,x,y,z都是正数,求xy+yz+xz-3xyz的最大值和最小值 已知 xy/x+y=1,yz/y+z=2,xz/x+z=3求x+y+z=? xy/x+y=1 yz/y+z=2 xz/x+z=3 求xyz/x+y+z=? x.y.z都大于0,xy+yz+xz=1,求1/(x+y)+1/(x+z)+1/(y+z)的最小值