3/(1+x^3)＝1/(1+x)－(x-2)/(1-x+x^2)＝1/(1+x)－1/2×(2x-1)/(1-x+x^2)＋3/2×1/[(x-1/2)^2＋3/4]所以,结果是ln|1+x|－1/2×ln|1-x+x^2|＋√3×arctan[(2x-1)/√]＋C
