Giải thích các bước giải:
\(\begin{array}{l}
a.\lim \frac{{2019.{{\left( {\frac{{2019}}{{2020}}} \right)}^n} + {{\left( {\frac{{2018}}{{2020}}} \right)}^n}}}{{\frac{{2019}}{{{{2020}^n}}} - 1}}\\
= \frac{0}{{ - 1}} = 0\\
b.\lim \frac{{\left( {2 + \frac{1}{n}} \right){{\left( {\frac{4}{n} - 5} \right)}^2}}}{{8 + \frac{8}{{{n^3}}}}} = \frac{{2.{{\left( { - 5} \right)}^2}}}{8}\\
= \frac{{25}}{4}
\end{array}\)
