Question

1/1+e^x的不定积分怎么求？数学老师快到碗里来～～～～～

Answer 1

简单计算一下即可，答案如图所示

Answer 2

let
y=e^x
dy = e^x dx
dx = dy/y
∫dx/(1+e^x)
=∫dy/[y(1+y)]
=∫[1/y-1/(1+y)]dy
=ln|y/(1+y)| + C
=ln|e^x/(1+e^x)| + C