Cho A = \(\frac{1}{1x2}+\frac{1}{3x4}+\frac{1}{4x5}+...+\frac{1}{99x100}\)
CM \(\frac{7}{12}\) < A < \(\frac{5}{6}\)
Cho A = \(\frac{1}{1x2}+\frac{1}{3x4}+...+\frac{1}{99x100}\)
Chứng minh \(\frac{7}{12}\) < A < \(\frac{5}{6}\)
\(\frac{1}{1x2}\)+ \(\frac{1}{2x3}+\frac{1}{3x4}+\frac{1}{4x5}+\frac{1}{5x6}\)+....\(\frac{1}{900}\)
bài này là Tính nhanh nha!
Tính \(\frac{A}{B}\) biết :A = \(\frac{1}{1x2}\)+ \(\frac{1}{3x4}\) +, \(\frac{1}{5x6}\)+...+ \(\frac{1}{17x18}\)+ \(\frac{1}{19x20}\) và B =\(\frac{1}{11}\) + \(\frac{1}{12}\)+ \(\frac{1}{13}\)+...+ \(\frac{1}{19}\)+ \(\frac{1}{20}\)Giúp mình với mình đang cần gấp . Ai nhanh mình tik cho!
Tính H=\(\frac{1}{1x2}\) -\(\frac{1}{1x2x3}\) +\(\frac{1}{2x3}\) -\(\frac{1}{2x3x4}\) +\(\frac{1}{3x4}\) -\(\frac{1}{3x4x5}\) +...+\(\frac{1}{99x100}\) -\(\frac{1}{99x100x101}\)
\(\frac{3}{1x2}+\frac{3}{2x3}+\frac{3}{3x4}+...+\frac{3}{99x100}\)
Tính ( Tính nhanh nếu có thể ) :
a , \(\frac{3}{40}+\frac{5}{3}+\frac{7}{60}\)
b , \(\frac{1}{1x2}+\frac{1}{2x3}+\frac{1}{3x4}+.....+\frac{1}{19x20}\)
Cho A = \(\frac{1}{1x2^2}+\frac{1}{2x3^2}+\frac{1}{3x4^2}+...+\frac{1}{49x50^2}\)
B = \(\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+...+\frac{1}{50^2}\)
CM A < \(\frac{1}{2}\) < B
Cho A = \(\frac{1}{1x2^2}+\frac{1}{2x3^2}+\frac{1}{3x4^2}+...+\frac{1}{49x50^2}\)
B = \(\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+...+\frac{1}{50^2}\)
CM A < \(\frac{1}{2}\) < B