f（x+y,xy）=x^2+y^2求fxy（1,

F(x+y)=f(x)+f(y)+2xy f'(0)=2fx定义域为r,求fx f（x,y）=sin（xy）,求fx（x,y）=? f(xy,x-y)=x^2+y^2,则fx(x,y)+fy(x,y)= 已知函数fx对任意xy∈R满足f(x+y)=f(x)+f(y)求 1 f(0)的值2 f(x)为奇函数 已知f（x）满足f（x+y）=fx+fy+2xy 且f1=2 求f（-3） f(x+y)=fx+fy+xy+1,则f1=1,求fx f(x+y,x-y)=(x^2-y^2)/2xy,求f(x,y)! f(x+y,x-y)=2xy(x-y),求f(x,y) f(xy,x-y)=x^2-xy+y^2.求f(x,y) y'=-2xy;求f(x). f(x,y)=xy^2+e^x,则fx(0,1)等于多少 函数fx满足关系f(xy)=f(x)+f(y) 求f(1/3)+f(1/2)+f(1)+f(2)+f(3) F(x+y)=fx+fy+2xy f'(0)=2 已知f(xy,（y^2）/x)=x^2+y^2,求f（（y^2）/x,xy） 设F(xy,y^2/x)=x^2+y^2,求F（y^2/x,xy） 偏导数f(x,y)=ln(x+y/2x),求fx(a,b) 设f(x+y,x-y)=x^2+xy,求f(x,y) f(x^2-y^2,x-y)=x+y+x^2-xy,求f'(x,y)对y求导