Hello,

I'm struggling to see the method of how this

$\displaystyle \frac{3}{1-e^{-4s}}\left\{\frac{1-e^{-2s}}{s}\right\}$ becomes $\displaystyle \frac{3}{s(1+e^{-2s})}$

It's the simplification of $\displaystyle \frac{1-e^{-2s}}{1-e^{-4s}}$ becoming $\displaystyle \frac{1}{1+e^{-2s}}$ that I'm not following...

Can anyone offer any pointers please? Thanks!