\(\frac{2}{2x5}+\frac{2}{5x8}+\frac{2}{8x11}+...+\frac{2}{96x98}=\frac{2}{3}\left(\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+...+\frac{1}{96}-\frac{1}{98}\right)\)
\(=\frac{2}{3}\left(\frac{1}{2}-\frac{1}{98}\right)=\frac{2}{3}x\frac{24}{49}=\frac{16}{49}\)
Chứng Minh: \(\frac{2}{2x5}\)+\(\frac{2}{5x8}\)+\(\frac{2}{8x11}\)+\(\frac{2}{11x14}\)+\(\frac{2}{14x17}\)< 1. Giải hẳn ra nhé
\(\frac{6}{2x5}+\frac{6}{5x8}+\frac{6}{8x11}+.......+\frac{6}{98x101}\)
\(\frac{1}{2x5}+\frac{1}{5x8}+\frac{1}{8x11}+\frac{1}{11x14}+\frac{1}{14x17}+\frac{1}{17x20}\)
Tính B = \(\frac{3}{2x5}+\frac{3}{5x8}+\frac{3}{8x11}+\frac{3}{11x14}\)
\(\frac{2}{5x8}+\frac{2}{8x11}+\frac{2}{11x14}+...+\frac{2}{95x98}\)
\(\frac{2}{5x8}+\frac{2}{8x11}+\frac{2}{11x14}+...+\frac{2}{95x98}\)
Tính tông A biết : $\frac{1}{5x8}+\frac{1}{8x11}+\frac{1}{11x14}+...+$
Tính: \(\frac{3}{5x8}+\frac{3}{8x11}+...+\frac{3}{605x608}+\frac{3}{608x611}\)
Tìm X biết \(\frac{1}{5x8}+\frac{1}{8x11}+\frac{1}{11x14}+...+\frac{1}{Xx\left(x+3\right)}=\frac{101}{1504}\)
