Tìm giới hạm của 2020n^2 - n / 2021 + n^2

Đáp án đúng là: D

Có \(\mathop {\lim }\limits_{n \to + \infty } \frac{{2020{n^2} - n}}{{2021 + {n^2}}}\)\[ = \mathop {\lim }\limits_{n \to + \infty } \frac{{2020 - \frac{1}{n}}}{{\frac{{2021}}{{{n^2}}} + 1}} = \frac{{\mathop {\lim }\limits_{n \to + \infty } \left( {2020 - \frac{1}{n}} \right)}}{{\mathop {\lim }\limits_{n \to + \infty } \left( {\frac{{2021}}{{{n^2}}} + 1} \right)}} = 2020\].

Vì \[\mathop {\lim }\limits_{n \to + \infty } \frac{1}{n} = 0\]; \[\mathop {\lim }\limits_{n \to + \infty } \frac{{2021}}{{{n^2}}} = 0\].