(1/x+1/y+1/z)×(xy)/(xy+yz+zx)

(1/x+1/y+1/z)×(xy)/(xy+yz+zx) (xy-1)^2+(x+y-z)(x+y-zxy)因式分解 x/zy + y/xz + z/xy >=1/x + 1/y + 1/z 证明 证明 当x+y+z=1时,x/yz+y/xz+z/xy≥9 若|x-3|+|y+2|+|2z+1|=0,求(xy-yz)(y-x+z) 求z=xy+1／x+1／y的极值 x²-y²+5x+3y+4（x+y-2xy)(x+y-z)+(xy-1）² 解方程组：x+y=2 ,xy+z=1 z=arctan【(x+y)/(1-xy)】的偏导数 xyz-xy-xz+x-yz+y+z-1因式分解 还是因式分解 xyz-xy-xz+x-yz+y+z-1 分解因式：xyz-yz-zx-xy+x+y+z-1 讨论函数z=arctan(x+y)/(1-xy)的连续性方程是z=arctan[(x+y)/(1-xy)] z=(1+xy)^y 就是（1+xy)的y次方z=(1+xy)^x就是（1+xy)的x次方 求dz (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=? z=(1+xy)^y 对y的偏导数=1+xy)^y *ln(1+xy)*x 对么? 若xyz=1,求 x/(xy+x+1) +y/(yz+y+z) +z/(zx+z+1)越快越好~.