cau hoi ban can co the o day https://lazi.vn/edu/exercise/tinh-h-a-1-1-2-2-1-1-3-2-1-1-n-2
\(\left(1+\frac{1}{2}\right)\left(1+\frac{1}{3}\right)\left(1+\frac{1}{4}\right).....\left(1+\frac{1}{n^2}\right)\)
\(=\)\(\frac{3}{2}.\frac{4}{3}.\frac{5}{4}.....\frac{n^2+1}{n^2}\)
\(=\)\(\frac{n^2+1}{2}\)
Chúc bạn học tốt ~