设f(x+y,xy)=x^2+y^2-xy,则（∂f(x,y)）/∂y=

设f(x+y,x-y)=x^2+xy,求f(x,y) 设f（x+y,xy）=x^2+y^2,则f（x,y） 设f(x+y,xy)=x^2+y^2-xy,则（∂f(x,y)）/∂y= 设函数f(xy,x+y)=x^2+y^2+xy,求∂f(x,y)／∂x和∂f(x,y)／∂y 设F(xy,y^2/x)=x^2+y^2,求F（y^2/x,xy） 设函数f(x,y)=xy/根号x^2+y^2,求limf(x,y)x,y趋于0 高数题 设f（x+y,x-y）=x^2-xy,则f(x,y)=多少 f(x+y)=f(x)+f(y)+2xy f(xy,x-y)=x^2+y^2+xy;f(x,y)/∂x;f(x,y)/∂y 设f(x+y,y/x)=x^2+y^2,则f(x,y)=?,f(x-y,xy)=? 设函数f(x,y)=(2xy)除以（x^2+y^2)求f（1,y/x) 设f(x-y,y/x)=xy,则f(xy,x+y)等于什么 设f(x-y,y/x)=xy,则f(xy,x+y)等于什么 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) 设z=f(x^2-y^2,e^（xy)),求偏导z/x,偏导z/y f(xy,x-y)=x^2+3xy+y^2,则f(x,y)=? f(xy,x-y)=x^2-xy+y^2.求f(x,y)