Các câu hỏi tương tự
a)A=\(\frac{1}{1\cdot3\cdot5}+\frac{1}{3\cdot5\cdot7}+\frac{1}{5\cdot7\cdot9}+...+\frac{1}{25\cdot27\cdot29}\)
b)\(\left(\frac{1}{1\cdot101}+\frac{1}{2\cdot102}+...+\frac{1}{10\cdot110}\right)\cdot x=\frac{1}{1.11}+\frac{1}{2\cdot12}+...+\frac{1}{100\cdot110}\)
Bài 1: Rút gọn rồi quy đồng
\(\frac{4\cdot5+4\cdot11}{8\cdot7-4\cdot3}\) \(\frac{-15\cdot8+10\cdot7}{5\cdot6+20\cdot3}\)và \(\frac{2^4\cdot5^2\cdot7}{2^3\cdot5\cdot7^3\cdot11}\)
\(A=\frac{1}{2\cdot3}+\frac{1}{6\cdot5}+\frac{1}{10\cdot7}+\frac{1}{14\cdot9}+....+\frac{1}{198\cdot101}\)
Tính: \(\frac{1}{1\cdot3}+\frac{1}{3\cdot5}+\frac{1}{5\cdot7}+...+\frac{1}{2003.2005}\)
Tính \(\frac{1\cdot3\cdot5\cdot7\cdot9...99}{50\cdot51\cdot52...100}\)
\(A=\frac{2}{1\cdot3\cdot5}\cdot\frac{2}{5\cdot7\cdot9}\cdot...\cdot\frac{2}{97\cdot99\cdot101}\)
tính
Tính tổng :\(P=\frac{1}{2\cdot3}+\frac{1}{6\cdot5}+\frac{1}{10\cdot7}+...+\frac{1}{198\cdot101}\)
Tính \(21\cdot\left(\frac{4}{1\cdot3}-\frac{8}{3\cdot5}+\frac{12}{5\cdot7}-\frac{16}{7\cdot9}+...+\frac{36}{17\cdot19}-\frac{40}{19\cdot21}\right)\)
\(D=1\cdot3\cdot5-3\cdot5\cdot7+5\cdot7\cdot9-...+97\cdot99\cdot101\)