We have indeterminateness of type
oo/oo,
i.e. limit for the numerator is
n→∞lim(2⋅2n)=∞and limit for the denominator is
n→∞lim2n=∞Let's take derivatives of the numerator and denominator until we eliminate indeterninateness.
n→∞lim(2−n2n+1)=
n→∞lim(dnd2ndnd2⋅2n)=
n→∞lim2=
n→∞lim2=
2It can be seen that we have applied Lopital's rule (we have taken derivatives with respect to the numerator and denominator) 1 time(s)