\(\frac{1}{2}A=\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{2014.2015}=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{2014}-\frac{1}{2015}\)
=1/2-1/2015=2013/4030
=>A=2013/2015
tick nhé
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 :
\(A=\frac{1}{1+2}+\frac{1}{1+2+3}+\frac{1}{1+2+3+4}+...+\frac{1}{1+2+3+...+2014}\)
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 \(A=\frac{1}{1^2}+\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+...+\frac{1}{2014^2}\)
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= \(\frac{2.2014}{1+\frac{1}{1+2}+\frac{1}{1+2+3}...+\frac{1}{1+2+3+4+...+2014}}\)
Tính: \(\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+\frac{1}{5^2}+...+\frac{1}{2014^2}\)
Tính : \(\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+\frac{1}{5^2}+...+\frac{1}{2014^2}\)
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 ~~~~
