函数f(x,y,z)=xy+yz+zx在点M(1,0,-1)处的梯度grandf(1,0,-1)=

函数z=f(x,y)由方程xy+yz+zx=1所确定,求fxy . 函数f(x,y,z)=xy+yz+zx在点M(1,0,-1)处的梯度grandf(1,0,-1)= x+y+z=1求 f=xy+yz+zx最大值 求由方程xy+yz+zx=1所确定的函数z=z(x,y),的偏导数fxy xy(x-y)+yz(y-z)+zx(z-x)因式分解 xy+yz+zx=1,求x√yz+y√zx+z√xy是小于等于 (1/x+1/y+1/z)×(xy)/(xy+yz+zx) 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) 求证不等式 xyz[yz(y+z)+zx(z+x)+xy(x+y)]>=2(xy+yz+xz)^2 如果xyz+xy+yz+zx+x+y+z=1975,求自然数x,y,z过程~ xy 2yz 3zx 4xyz________ = ________ = _______ = ___________ (xyz不等于0)x+y+xy y+z+yz z+x+zx xy+yz+zx最好有解题思路 算出 X Y Z 分别等于几 (x+y+z)(xy+yz+zx)等于多少 分解因式：xyz-yz-zx-xy+x+y+z-1 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=? 若x+y+z=6,xy+yz+zx=11,xyz=6,则x/yz+y/zx+z/xy= 若x+y+z=6,xy+yz+zx=11,xyz=6,则x/yz+y/zx+z/xy= XYZ满足XY/X+Y=-2,YZ/Y+Z=3/4,ZX/Z+X=-4/3,求XYZ/XY+YZ+ZX的值 已知yz+zx+xy=1,确定的z=z(x,y),求dz.