2.设函数f(x,y)=xy,则fy(x,y)为( ) A.yxy-1 B.xylnx C.xylny D.xy

问题描述:

2.设函数f(x,y)=xy,则fy(x,y)为( ) A.yxy-1 B.xylnx C.xylny D.xy

B