We have indeterminateness of type
oo/oo,
i.e. limit for the numerator is
x→∞lim4x=∞and limit for the denominator is
x→∞limx=∞Let's take derivatives of the numerator and denominator until we eliminate indeterninateness.
x→∞lim(x4x)=
x→∞lim(dxdxdxd4x)=
x→∞lim(2⋅4xlog(2))=
x→∞lim(2⋅4xlog(2))=
∞It can be seen that we have applied Lopital's rule (we have taken derivatives with respect to the numerator and denominator) 1 time(s)