(x^2+yz)/(x^2+x(y-z)-yz)+(y^2-xz)/(y^2+y(x+z)+zx)+(z^2+yx)/(
(x^2+yz)/(x^2+x(y-z)-yz)+(y^2-xz)/(y^2+y(x+z)+zx)+(z^2+yx)/(
(2X+Z-Y)/(X^2-XY+XZ-YZ)-(Y-Z)/(X^2-XY-XZ+YZ)
解方程组xy+xz=8-x^2,yx+yz=12-y^2,zy+zx=-4-z^2
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-
化简(2x-y-z/x^2-xy-xz+yz)+(2y-x-z/y^2-xy-yz+xz)+(2x-x-y/z^2-xz
求(2X+Z-Y)/(X^2-XY+XZ-YZ)-(2X+Y+Z)/(X^2+XY+XZ+YZ)
证明 (x+y+z)^2>3(xy+yz+zx)
设f(x,y,z)=x.arcsiny+yz^2+zx^2,求f(xz),f(yz),f(zz)
已知x^2/(y^2+z^2+yz)+y^2/(x^2+z^2+zx)+z^2(y^2+x^2+yx)>=1
xy(x^2-y^2)+yz(y^2-z^2)+zx(z^2-x^2)
分式题:xy=x+y,yz=2(y+z),zx=3(z+x),求xyz/(xy+yz+xz)
已知三个数x y z 满足 xy/x+y=-2,yx/y+x=4/3,zx/z+x=-4/3,则xyz/xy+xz+yz