1 1/13 x 1 1/14 x ........... x 1 1/2014 = 14/13 x 15/14 x ...... x 2015/2014 = (14 x 15 x ....x 2014) x 2015/( 14 x 15 x .......x2014) x 13 = 2015/13
tính nhanh: \(1\frac{1}{4}\times1\frac{1}{8}\times1\frac{1}{15}\times1\frac{1}{24}\times1\frac{1}{35}\times...\times1\frac{1}{9800}\)
Tính nhanh:
a) 12,5 x 40,7 + 59,3 x 12,5
b) 1,9 + 1,8 + 1,7 + 1,6 + 1,5 + 1,4 + 1,3 + 1,2 + 1,1
c) \(1\frac{1}{10}\times1\frac{1}{11}\times1\frac{1}{12}\times1\frac{1}{13}\times1\frac{1}{14}\times1\frac{1}{15}\times1\frac{1}{16}\)
Tính nhanh \(1\frac{1}{15}\times1\frac{1}{16}\times1\frac{1}{17}\times...\times1\frac{1}{2009}\times1\frac{1}{2010}\)
Tinh nhanh:
\(1\frac{1}{3}\times1\frac{1}{8}\times1\frac{1}{15}\times...\times1\frac{1}{9800}\)
N = \(1\frac{1}{3}\times1\frac{1}{8}\times1\frac{1}{15}\times1\frac{1}{24}\times...\times1\frac{1}{99}\)
Tìm số tự nhiên X biết \(1\frac{1}{5}\times1\frac{1}{6}\times1\frac{1}{7}\times...\times1\frac{1}{2014}\) =X
\(1\frac{1}{3}\times\frac{1}{8}\times1\frac{1}{15}\times.....\times1\frac{1}{9800}\)
Tính A=112×113×114....×112016×112017A=1\frac{1}{2}\times1\frac{1}{3}\times1\frac{1}{4}....\times1\frac{1}{2016}\times1\frac{1}{2017}A=121×131×141....×120161×120171
Tính thuận tiện
a) \(1\frac{1}{2}\times1\frac{1}{3}\times1\frac{1}{4}\times...\times1\frac{1}{2014}\)
b) \(1\frac{1}{3}\times1\frac{1}{8}\times1\frac{1}{15}\times...\times1\frac{1}{99}\)
c) \(\frac{1x2+2x4+3x6+4x8+5x10}{1x3+2x6+3x9+4x12+5x15}\)
d) \(\frac{1}{10}+\frac{4}{20}+\frac{9}{30}+\frac{16}{40}+\frac{25}{50}+\frac{36}{40}+\frac{49}{70}+\frac{64}{80}+\frac{81}{90}\)
e)\(\frac{10}{20}x\frac{2020}{3030}x\frac{303030}{404040}x...x\frac{808080...80}{909090...90}\) f)\(\frac{100x100-1}{99x101}\)
g) \(\frac{1-\frac{2}{25}+\frac{5}{6}+\frac{3}{4}}{2-\frac{4}{25}+\frac{5}{3}+\frac{3}{2}}\)
