积分的计算方式？

Question

如题所述

Answer 1

联通积分的计算基本方法为：当月积分＝当月通信消费积分＋当月奖励积分＋当月特殊积分，1积分相当于人民币0.01元。

Answer 2

let
u=-t
du=-dt
t=-π/2, u=π/2
t=π/2, u=-π/2
∫(-π/2->π/2) (sint)^2/(1+e^t) dt

=∫(π/2->-π/2) [(sinu)^2/(1+e^(-u)) ] (-du)
=∫(-π/2->π/2) [(sinu)^2/(1+e^(-u)) ] du
=∫(-π/2->π/2) [(sint)^2/(1+e^(-t)) ] dt
=∫(-π/2->π/2) [e^t. (sint)^2/(1+e^t) ] dt
=∫(-π/2->π/2) [(sint)^2 - (sint)^2/(1+e^t) ] dt
2∫(-π/2->π/2) (sint)^2/(1+e^t) dt =∫(-π/2->π/2) (sint)^2dt

∫(-π/2->π/2) (sint)^2/(1+e^t) dt =(1/2)∫(-π/2->π/2) (sint)^2dt

Answer 3