设f(x+y,xy)=x^2+y^2-xy,则(∂f(x,y))/∂y=

问题描述:

设f(x+y,xy)=x^2+y^2-xy,则(∂f(x,y))/∂y=

f(x+y,xy)=x^2+y^2-xy
=(x+y)^2-3xy
f(x,y)=x^2-3y
(∂f(x,y))/∂y= -3