用分部积分,u=arctanx dv=1/x^2 dx
∫1/x^2 arctanxdx
=-arctanx/x+∫dx/[x(1+x^2)]
=-arctanx/x+∫ [1/x - x/(1+x^2)]dx
=-arctanx/x+ln|x|-1/2ln(1+x^2)+C
用分部积分,u=arctanx dv=1/x^2 dx
∫1/x^2 arctanxdx
=-arctanx/x+∫dx/[x(1+x^2)]
=-arctanx/x+∫ [1/x - x/(1+x^2)]dx
=-arctanx/x+ln|x|-1/2ln(1+x^2)+C