Tính giới hạn:

B

- Hướng dẫn giải

Đáp án B

$$\begin{gathered} \lim \left[\left(1-\frac{1}{2^2}\right)\left(1-\frac{1}{3^2}\right)\mathrm{...}\left(1-\frac{1}{n^2}\right)\right] \\ =\lim \left[\frac{1.3}{2^2}.\frac{2.4}{3^2}.\frac{3.5}{4^2}\mathrm{...}\frac{\left(n-1\right)\left(n+1\right)}{n^2}\right] \\ =\lim \frac{1}{2}.\frac{n+1}{n}=\frac{1}{2} \end{gathered}$$