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lta2151995
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Cho [TEX]a_1,a_2,...,a_2009[/TEX] là 2009 số thực có dạng
[TEX]a_k[/TEX]=[TEX]\frac{2k+1}{(k^2+k)^2}[/TEX]
k=[TEX]\overline{1,2009}[/TEX]
Tính [TEX]S_2009[/TEX]=[TEX]a_1+a_2+...+a_2009[/TEX]
[TEX]a_k[/TEX]=[TEX]\frac{2k+1}{(k^2+k)^2}[/TEX]
k=[TEX]\overline{1,2009}[/TEX]
Tính [TEX]S_2009[/TEX]=[TEX]a_1+a_2+...+a_2009[/TEX]