lim 2n^-n+1/n^3+n bằng:

Đáp án đúng là: D

Ta có $\lim \frac{2n^2-n+1}{n^3+n}=\lim \frac{\frac{2}{n}-\frac{1}{n^2}+\frac{1}{n^3}}{1+\frac{1}{n^2}}$

Do $\lim \left(\frac{2}{n}-\frac{1}{n^2}+\frac{1}{n^3}\right)=0$

Mà lại có $\lim \left(1+\frac{1}{n^2}\right)=1$

Suy ra $\lim \frac{2n^2-n+1}{n^3+n}=\lim \frac{\frac{2}{n}-\frac{1}{n^2}+\frac{1}{n^3}}{1+\frac{1}{n^2}}=0.$