怎么把xy+(yz+zx)2化简
xy 2yz 3zx 4xyz
化简x^2-yz/[x^2-(y+z)x+yz]+y^2-zx/[y^2-(z+x)y+zx]+z^2-xy/[z^2-
证明 (x+y+z)^2>3(xy+yz+zx)
已知xy:yz:zx=3:2:1,求①x:y:z ②x/yz:y/zx
XYZ满足XY/X+Y=-2,YZ/Y+Z=3/4,ZX/Z+X=-4/3,求XYZ/XY+YZ+ZX的值
x+y分之xy=5,y+z分之yz=2分之7,z+x分之zx=4,则xy+yz+zx分之xyz=?
xy+yz+zx=1,求x√yz+y√zx+z√xy
catia如何看面``就是一共是XY、yz、zx这几个面怎么分清楚..
(1/x+1/y+1/z)×(xy)/(xy+yz+zx)
xy(x^2-y^2)+yz(y^2-z^2)+zx(z^2-x^2)
解方程组 xy=2,yz=3,zx=2
已知xy:yz:zx=3:2:1,求(x+y):z的值