Question

\(\frac{1}{6\cdot10}+\frac{1}{7\cdot9}+\frac{1}{8\cdot8}+\frac{1}{9\cdot7}+\frac{1}{10\cdot6}\)

Answer 1

Đặt dãy trên là A

Khi đó \(A=\frac{2}{6\times10}+\frac{2}{7\times9}+\frac{1}{64}\)

\(A=\frac{1}{30}+\frac{2}{63}+\frac{1}{64}\)

\(A=\frac{672}{20160}+\frac{640}{20160}+\frac{315}{20160}=\frac{1627}{20160}\)

Answer 2

Nguyenhoangtien sai bét

Answer 3

Đặt phép tính trên là A, ta có

\(A=\left(\frac{1}{6\cdot10}+\frac{1}{10\cdot6}\right)+\left(\frac{1}{7\cdot9}+\frac{1}{9\cdot7}\right)+\frac{1}{8\cdot8}\)

\(A=\frac{1}{30}+\frac{2}{63}+\frac{1}{64}\)

\(A=\frac{672}{20160}+\frac{640}{20160}+\frac{315}{20160}\)

\(A=\frac{1627}{20160}\)