设f(xy,x+y)=x2+y2,则∂f(x,y)/∂x+∂f(x,y)/∂y=____.
-2+2y。 解析:f(xy,x+y)=x2+y2=x2+2xy+y2-2xy =-2xy+(x+y)2,所以f(x,y)=-2x+y2,因此∂f(x,y)/ ∂x+ ∂f(x,y)/ ∂y=-2+2y
设f(xy,x+y)=x2+y2,则∂f(x,y)/∂x+∂f(x,y)/∂y=____.
-2+2y。 解析:f(xy,x+y)=x2+y2=x2+2xy+y2-2xy =-2xy+(x+y)2,所以f(x,y)=-2x+y2,因此∂f(x,y)/ ∂x+ ∂f(x,y)/ ∂y=-2+2y