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duonghongsonmeo
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rút gọn
[tex] A=\frac{1}{3} - \frac{1}{3^{2}}+ \frac{1}{3^{3}}-\frac{1}{3^{4}}+...-\frac{1}{3^{2010}}+\frac{1}{3^{2011}}[/tex]
[tex] A=\frac{1}{3} - \frac{1}{3^{2}}+ \frac{1}{3^{3}}-\frac{1}{3^{4}}+...-\frac{1}{3^{2010}}+\frac{1}{3^{2011}}[/tex]
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