若x/2=y/3=z/4,求（xy+yz+zx）/（x²+y²+z²）的值.

若|x-3|+|y+2|+|2z+1|=0,求(xy-yz)(y-x+z) 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) 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 XYZ满足XY/X+Y=-2,YZ/Y+Z=3/4,ZX/Z+X=-4/3,求XYZ/XY+YZ+ZX的值 数学题 xy&x+y =-2,yz&y+z=4&3 zx&z+x=-4&3 求XYZ%xy+xz+yz 若x/3=y=z/4,且xy+xz+yz=76,求2x*x+12y*y+9z*z的值 若x-3=y-2=z-1,求x^+y^+z^-xy-yz-xz的值,若x-3=y-2=z-1,求x^+y^+z^-xy-yz-xz的值 若x/2=1/y=z/3,且xy+xz+yz=99,求4x^2-2xz+3yz-9y^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 已知x/2=y/3=z/4求(Xy+yz+zx)/(x^2+y^2+z^2) x/3=y/4=z/5 求xy+yz+zx/x^2+y^2+z^2的值 若/x+3/+/y-2/+/2z+1/=0,求(xy-yz)(y-x+z)的值 已知,x/2=y/3=z/4,求xy+yz+zx/x2+y2+z2????? 方程组xy/x+y=2 yz/y+z=4 zx/x+z=5 求x,y,z 当X/2=Y/3=Z/4时,求X-2Y+3Z/XY+2YZ+3YZ的值 已知x /2=y/3=z/4,求代数式x-2y+3z/xy+2yz+3yz的值 若Y/X=3/2,Y/Z=3/4.则2XY+YZ/2YZ-XY=多少