I'm stumped by the following limit: $\lim_{x\rightarrow\infty}2x(a+x(e^{-a/x}-1))$
Mathematica gives the answer as $a^2$ but I'd like to know the evaluation steps. I've staring at it for a while, but can't figure it out. Seems like you can't use L'Hopital's rule on this one. I've tried substitution $y=1/x$ but that didn't help. I am probably not seeing something simple. Any hints?