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

证明 当x+y+z=1时,x/yz+y/xz+z/xy≥9 若|x-3|+|y+2|+|2z+1|=0,求(xy-yz)(y-x+z) 设x,y,z∈R+,xy+yz+xz=1,证明不等式:(xy)^2/z+(xz)^2/y+(yz)^2/x+6xyz≥x+y+zRt (x+y-xy)/(x+y+2xy)=(y+z-2yz)/(y+z+3yz)=(z+x-3zx)/(z+x+4zx),且2/x=3/y=1/z,则xyz=? 已知（x+y-xy）/(x+y+2xy)=(y+z-2yz)/(y+z+3yz)=(z+x-3zx)/(z+x+4zx),且2/x=3/y-1/z,则xyz=? xy+yz+zx=1,求x√yz+y√zx+z√xy是小于等于 xy/x+y=1/27 yz/y+z=1/33 xz/x+z=1/30,求x,y,z, 若xyz=1,求 x/(xy+x+1) +y/(yz+y+z) +z/(zx+z+1)越快越好~. 已知yz+zx+xy=1,确定的z=z(x,y),求dz. x+y+z=5,xy+xz+yz=1 ,求Z的最小值和最大值 若|x-3|+|y+z|+|2z+1|=0,求XY-YZ的值 若｜x-3｜+｜y+z｜+｜2z+1｜=0,求xy-yz的值 已知xy/x+y=3,yz/y+z=2,zx/z+x=1,求y的值 (1/x+1/y+1/z)×(xy)/(xy+yz+zx) 已知xy(x+y)^-1=1,yz(y+z)^-1=2,xz(z+x)^-1=3,试求xyz(xy+yz+xz)^-1的值 已知xy(x+y)^-1=1,yz(y+z)^-1=2,xz(z+x)^-1=3,试求xyz(xy+yz+xz)^-1的值 已知xy/(x+y)=1,yz/(y+z)=2,zx/(z+x)=3,求x的值 xy/x+y=1,xz/x+z=2,yz/y+z=3,求x的值