x/3=y/4=z/5 求xy+yz+zx/x^2+y^2+z^2的值

已知XY=2(X+Y),YZ=4(Y+Z),ZX=5(Z+X),求X,Y,Z已知XY=2(X+Y),YZ=4(Y+Z),ZX=5(Z+X),求X,Y,Z 方程组xy/x+y=2 yz/y+z=4 zx/x+z=5 求x,y,z 方程组：(x+y)/xy=3 (y+z)/yz=4 (z+x)/xz=5 X+Y+Z=5,XY+XZ+YZ=3求Z范围 x/3=y/4=z/5 求xy+yz+zx/x^2+y^2+z^2的值 若实数x,y,z满足x+y+z=5,xy+yz+xz=3,求z的最大值 实数x,y,z满足x+y+z=5,xy+yz+zx=3,求z的最大值 时数x,y,z满足x+y+z=5,xy+yz+zx=3,求Z最大值 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) 已知x+y+yz=5,y+z+xy=8,x+z+xy=9,求x,y,z 知x/3=y/4=z/5,求(xy+yz+xz)/xx+yy+zz xy/x+y=6/5 yz/y+z=12/7 xz/x+z=4/3 求x和y和z 已知4x-5y+2z=0,x+4y-3z=0,求(x²+y²+z²)/xy+yz+xz 若|x-3|+|y+2|+|2z+1|=0,求(xy-yz)(y-x+z) 已知1/x=5/y+z=3/z+x 求2xy/yz ÷x/Y的值 x,y,z为实数,且xy/x+y=1/3,yz/y+z=1/4,xz/x+z=1/5,求xyz/xy+yz+zx的值 数学高手解一道分式计算题,一定要写过程x.y.z为实数,且xy/x+y=1/3,yz/y+z=1/4,xz/x+z=1/5,求xyz/xy+yz+zx X,Y,Z为实数,且XY/X+Y=1/3,YZ/Y+Z=1/4,XZ/X+Z=1/5,求XYZ/XY+YZ+XZ的值帮帮忙,谢谢