用分部积分法∫arctanxdx = xarctanx - ∫xdarctanx= xarctanx - ∫[x/(1+x^2)]dx = xarctanx - (1/2)∫[d(1+x^2)/(1+x^2)]= xarctanx - (1/2)ln(1+x^2) + C2
