使用mathwayhttp://www.mathway.com/answer.aspx?p=ccal?p=f(x)SMB01xsinx+1SMB102cosx?p=409?p=?p=?p=?p=?p=?p=?p=0?p=?p=
cosx在分子还是分母上?我算的是在分子上的y'=xcosx+1/2sinx