arctanx的导数是什么 arctanx的导数多少 arctanx的导数是什么?arctanx的导数是1/1+x,设y=arctanx,则x=tany,因为arctanx′=1/tany′,且tany′=(siny/cosy)′=cosycosy-siny(-siny)/cosy=1/cosy,则arctanx′=cosy=cosy/siny+co...