求下列不定积分：∫[1/(1+e2x)]dx

求下列不定积分：∫[1/(1+e^2x)]dx
【正确答案】：∫[dx/(1+e^2x)]=∫(1+e^2x-e^2x)/(1+e^2x)=x-(1/2)ln(1+e^2x)+c．