![](https://lstatic.shangxueba.com/jiandati/pc/images/pc_jdt_tittleico.png)
设f(x,y)=,求fX(x)和fY(y)。
设f(x,y)=,求fX(x)和fY(y)。
![](https://lstatic.shangxueba.com/jiandati/pc/images/jdt_panel_vip.png)
设f(x,y)=,求fX(x)和fY(y)。
A.fx(x0,y0)=0,fy(x0,y0)=0
B.[fxy(x0,y0)]2-fxx(x0,y0)fyy(x0,y0)<0
C.fx(x0,y0)=0,fy(x0,y0)=0,[fxy(x0,y0)]2-fxx(x0,y0)fyy(x0,y0)<0,fxx(x0,y0)>0
D.fx(x0,y0)=0,fy(x0,y0)=0,[fxy(x0,y0)]2-fxx(x0,y0)fyy(x0,y0)<0,fxx(x0,y0)<0
A.必要
B.充分必要
C.既不充分也不必要
D.充分
A.Px→$y(Sy∧Fxy)
B.Py→$y(Sy∧Fyy)
C.Px→$y(Sy∧Fzy)
D.Pa→$y(Sy∧Fay)
设f(x,y,z)=xy2+yz2+zx2,求fxx(0,0,1),fxz(1,0,2),fyz(0,-1,0).
设f(x,y,z)=xy2+yz2+zx2求fxx(0,0,1),fxz(1,0,2),fyz(0,-1,0).
设fx,fy和fyx在点(x0,y0)的某邻域内存在,fyx在点(x0,y0)连续,证明fxy(x0,y0)也存在,且fxy(x0,y0)=fyx(x0,y0).
已知函数f(x,y,z)=xy2+yz2+zx2,求fxx(0,0,1),fxz(1,0,2),fyz(0,-1,0),fzx(2,0,1).
设fx,fy,和fyx在点(x0,y0)的某领域内存在,fyx在点(x0,y0)连续,证明fxy在点(x0,y0)也存在,且fxy(x0,y0)=fyx(x0,y0).
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