\(\mathop {\lim }\limits_{} {\mkern 1mu} \frac{{{{2.3}^n} - {5^{n + 1}}}}{{{2^n} + {5^n}}}\) bằng 

* Hướng dẫn giải

\(\mathop {\lim }\limits_{} {\mkern 1mu} \frac{{{{2.3}^n} - {5^{n + 1}}}}{{{2^n} + {5^n}}} = \mathop {\lim }\limits_{} {\mkern 1mu} \frac{{2.{{\left( {\frac{3}{5}} \right)}^n} - 5}}{{{{\left( {\frac{2}{5}} \right)}^n} + 1}} =  - 5\)