Gevraagd: $
\eqalign{\mathop {\lim }\limits_{x \to \infty } \frac{{n^2 \cos \left( n \right)}}
{{2^n }}}
$
$
\eqalign{
& \mathop {\lim }\limits_{n \to \infty } \frac{{n^2 \cdot \cos (n)}}
{{2^n }} \cr
& \frac{{ - n^2 }}
{{2^n }} \leq \frac{{n^2 \cdot \cos (n)}}
{{2^n }} \leq \frac{{n^2 }}
{{2^n }} \cr
& \mathop {\lim }\limits_{n \to \infty } \frac{{ - n^2 }}
{{2^n }} = 0\,\,en\,\,\mathop {\lim }\limits_{n \to \infty } \frac{{n^2 }}
{{2^n }} = 0 \cr
& \mathop {\lim }\limits_{n \to \infty } \frac{{n^2 \cdot \cos (n)}}
{{2^n }} = 0 \cr}
$