Giải thích các bước giải:
$\begin{array}{l}
\lim \dfrac{{{3^n} + {5^{n + 1}}}}{{{{3.4}^n} + {5^{2n}}}}\\
= \lim \dfrac{{{3^n} + {{5.5}^n}}}{{{{3.4}^n} + {{25}^n}}}\\
= \lim \dfrac{{{{\left( {\dfrac{3}{{25}}} \right)}^n} + 5.{{\left( {\dfrac{1}{5}} \right)}^n}}}{{3.{{\left( {\dfrac{4}{{25}}} \right)}^n} + 1}}\\
= \dfrac{{0 + 5.0}}{{3.0 + 1}}\\
= 0
\end{array}$
