∫(上限ln2,下限0) e^x/1+e^2x dx
问题描述：
∫(上限ln2,下限0) e^x/1+e^2x dx
答
∫[0,ln2] e^x/(1+e^2x )dx
=∫[0,ln2] 1/(1+e^2x )de^x
=arctane^x[0,ln2]
=arctan2-π/4