\(\frac{3}{5.8}+\frac{3}{8.11}+...+\frac{3}{21.24}\)
\(=\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+...+\frac{1}{21}-\frac{1}{24}\)
\(=\frac{1}{5}-\frac{1}{24}\)
\(=\frac{19}{120}\)
Tính : \(\frac{3}{2.5}+\frac{3}{5.8}+\frac{3}{8.11}+\frac{3}{11.14}+\frac{3}{14.17}\)
Tính : \(A=\frac{3}{5.8}+\frac{3}{8.11}+\frac{3}{11.14}+...+\frac{3}{2009.2012}+\frac{3}{2012.2015}\)
B=\(\frac{3}{5.8}+\frac{3}{8.11}+\frac{3}{11.14}+...+\frac{3}{2018.2021}\)
Tính H=\(\frac{3^2}{1.5}+\frac{3^2}{5.8}+\frac{3^2}{8.11}+\frac{3^2}{11.14}+...+\frac{3^2}{197.200}\)
\(\frac{3^2}{2.5}+\frac{3^2}{5.8}+\frac{3^2}{8.11}+\frac{3^2}{11.14}+\frac{3^2}{14.172}\)
Tính tổng sau:
a) S= 1 + \(\frac{3}{2.5}+\frac{3}{5.8}+\frac{3}{8.11}+\frac{3}{11.14}+...+\frac{3}{24.27}+\frac{3}{27.30}\)
b) S= -4 + \(\frac{3}{1.4}+\frac{3}{4,7}+\frac{3}{7.10}+...+\frac{3}{103.107}+\frac{3}{107.110}\)
tính các tổng sau
B=\(\frac{3}{2.5}+\frac{3}{5.8}+\frac{3}{8.11}+\frac{3}{11.14}\)
C=\(\frac{3}{4}+\frac{3}{28}+\frac{3}{70}+\frac{3}{130}+\frac{3}{208}\)
giải giúp mình nha
Tìm x, biết
1, \(x+\frac{3}{5.8}+\frac{3}{8.11}+\frac{3}{11.14}+...+\frac{3}{32.35}=\frac{-29}{35}\)
Tìm x , biết : \(\frac{1}{5.8}+\frac{1}{8.11}+\frac{1}{11.14}+...+\frac{1}{x.(x+3)}=\frac{101}{1504} \)