设z=f(xy)-xsin(xy),若当x=1时,有z=y,则z=?谁告诉我怎么求啊.

Question

设z=f(xy)-xsin(xy),若当x=1时,有z=y,则z=?
谁告诉我怎么求啊.

Answer 1

把x=1代入z=f(xy)-xsin(xy)
得f(y)=y+siny
因此,f(xy)=xy+sinxy
z=f(xy)-xsin(xy)
=xy+sinxy-xsin(xy)
=xy+(1-x)sin(xy)