若x/3=y/1=z/2,且xy+yz+zx=99,求zx平方+9y平方+9z平方的值?

若|x-3|+|y+2|+|2z+1|=0,求(xy-yz)(y-x+z) (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=? 若x,y,z都是正实数,且x^2+y^2+z^2=1,求证yz/x+xz/y+xy/z>=根号3 若x/2=1/y=z/3,且xy+xz+yz=99,求4x^2-2xz+3yz-9y^2的值. 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 若x/3=y/1=z/2,且xy+yz+zx=99,那麽2x^2+12y^2+9z^2=? 若x/3=y/1=z/2,且xy+yz+zx=99,则2x^2+12y^2+9z^2= 若X/3=Y/1=Z/4,且XY+XZ+YZ=76,求2X^2+12Y^2+9Z^2的值 若x/3=y/2=z/5,且xy+yz+zx=93,求9x*x+12y*y+2z*z的值. 若x:y:z=3:1:2,且zx-xy-yz=99,求2x^2+12y^2+9z^2的值 若x/3=y=z/4,且xy+xz+yz=76,求2x*x+12y*y+9z*z的值 若x/3=y/1=z/4,且xy+xz+yz=76,求2x²+12y²+9z²的值 若x,y,z都是正实数,且x^2+y^2+z^2=1,则yz/x+xz/y+xy/z的最小值是多少? 若Y/X=3/2,Y/Z=3/4.则2XY+YZ/2YZ-XY=多少 若Y/X=3/2,Y/Z=3/4.则(2XY+YZ)/(2YZ-XY)=多少 分式题:xy=x+y,yz=2(y+z),zx=3(z+x),求xyz/(xy+yz+xz)xy=x+y,yz=2(y+z),zx=3(z+x),求xyz/(xy+yz+xz)