Giải thích các bước giải:
$\lim (1-\dfrac{1}{2^2})(1-\dfrac{1}{3^2})...(1-\dfrac{1}{n^2})$
$=\lim \dfrac{2^2-1}{2^2}.\dfrac{3^2-1}{3^2}....\dfrac{n^2-1}{n^2}$
$=\lim \dfrac{1.3}{2^2}.\dfrac{2.4}{3^2}....\dfrac{(n-1)(n+1)}{n^2}$
$=\lim \dfrac{(1.2...(n-1)).(3.4..(n+1))}{(2.3.4..n)^2}$
$=\lim \dfrac{n+1}{2n}$
$=\lim \dfrac 12+\dfrac{1}{2n}=\dfrac 12$