Các câu hỏi tương tự
Tính
\(\frac{1\cdot3\cdot5\cdot7...99}{50\cdot51\cdot52...100}\)
Cho \(U_1=\frac{1}{1\cdot3\cdot5}\); \(U_2=\frac{1}{1\cdot3\cdot5}+\frac{1}{3\cdot5\cdot7}\); \(U_3=\frac{1}{1\cdot3\cdot5}+\frac{1}{3\cdot5\cdot7}+\frac{1}{5\cdot7\cdot9}\)
a) Lập quy trình tổng quát tính Un
b) Tính U50, U60
c) Tính U1002
Tính nhanh :
\(A=\left(1-\frac{2}{6\cdot7}\right)\left(1-\frac{2}{7\cdot8}\right)\left(1-\frac{2}{8\cdot9}\right)\cdot\cdot\cdot\left(1-\frac{2}{51\cdot52}\right)\)
\(B=\left(1+\frac{1}{1\cdot3}\right)\left(1+\frac{1}{2\cdot4}\right)\left(1+\frac{1}{3\cdot5}\right)\cdot\cdot\cdot\left(1+\frac{1}{99\cdot101}\right)\)
a)A=\(\frac{1}{1\cdot3\cdot5}+\frac{1}{3\cdot5\cdot7}+\frac{1}{5\cdot7\cdot9}+...+\frac{1}{25\cdot27\cdot29}\)
b)\(\left(\frac{1}{1\cdot101}+\frac{1}{2\cdot102}+...+\frac{1}{10\cdot110}\right)\cdot x=\frac{1}{1.11}+\frac{1}{2\cdot12}+...+\frac{1}{100\cdot110}\)
\(D=1\cdot3\cdot5-3\cdot5\cdot7+5\cdot7\cdot9-...+97\cdot99\cdot101\)
\(A=\frac{2}{1\cdot3\cdot5}\cdot\frac{2}{5\cdot7\cdot9}\cdot...\cdot\frac{2}{97\cdot99\cdot101}\)
tính
\(A=\frac{1}{2\cdot3}+\frac{1}{6\cdot5}+\frac{1}{10\cdot7}+\frac{1}{14\cdot9}+....+\frac{1}{198\cdot101}\)
Giúp mk bài này nha.
Tính : \(B=1\cdot3^3+3\cdot5^3+5\cdot7^3+...+49\cdot51^3\)
Tính \(21\cdot\left(\frac{4}{1\cdot3}-\frac{8}{3\cdot5}+\frac{12}{5\cdot7}-\frac{16}{7\cdot9}+...+\frac{36}{17\cdot19}-\frac{40}{19\cdot21}\right)\)