Question

improper integral

Answer 1

\[\int\limits_{-\infty}^{-3}\frac{ e ^{5x} }{ 1+e ^{5x} } dx\]

Answer 2

From Mathematica v9:
\[\int\limits_{-\infty }^{-3} \frac{e^{5 x}}{e^{5 x}+1} \, dx=\frac{1}{5} \left(1+e^{15}\right) \log -3 \]

Answer 3

Do integration by substitution with \(y=-x\), rearrange and then you may be able to see what you need to do from there

Answer 4

if my hint is not enough, i'll.... do something. Ask ^_^

Answer 5

i got it! :) thanks.