\(a_{n-1}=\frac{2}{n\left(n+1\right)}=\frac{2}{n}+\frac{2}{n+1}\)
\(A=\frac{2}{2}-\frac{2}{3}+\frac{2}{3}-\frac{2}{4}+\frac{2}{4}-\frac{2}{5}+.......+\frac{2}{2014}-\frac{2}{2015}=1-\frac{2}{2015}=\frac{2013}{2015}\)
Tính tổng \(S=2014+\frac{2014}{1+2}+\frac{2014}{1+2+3}+\frac{2014}{1+2+3+4}\)\(+...+\frac{2014}{1+2+3+...+10000}\)
Tính tổng : \(A=1+\frac{1}{1+2}+\frac{1}{1+2+3}+...+\frac{1}{1+2+3+...+2014}\)=?
Tính \(A=\frac{1}{1^2}+\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+...+\frac{1}{2014^2}\)
\(A=\frac{1}{1^2}+\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+...+\frac{1}{2014^2}\)
Tính A
Tính A=\(\left(1-\frac{1}{1+2}\right).\left(1-\frac{1}{1+2+3}\right).\left(1-\frac{1}{1+2+3+4}\right).....\left(1-\frac{1}{1+2+3+...+2014}\right)\)
Tính \(\frac{1}{1+2}+\frac{1}{1+2+3}+\frac{1}{1+2+3+4}+...+\frac{1}{1+2+3+...+2014}\)
Tính A = \(\frac{1}{1+2}+\frac{1}{1+2+3}+\frac{1}{1+2+3+4}+.....+\frac{1}{1+2+3+.....+2014}\)
Help me ~~~~
Tính B=\(\frac{2016}{1+\frac{1}{1+2}+\frac{1}{1+2+3}+...+\frac{1}{1+2+3+...+2014}+\frac{1}{1+2+3+...+2015}}\)
Tính :
D= \(\frac{2.2014}{1+\frac{1}{1+2}+\frac{1}{1+2+3}...+\frac{1}{1+2+3+4+...+2014}}\)
