[tex]1+\frac{1}{3} + \frac{1}{ {3}^{2} } + \frac{1}{ {3}^{3} } + ........ + \frac{1}{ {3}^{100} } = s .atunci \: calculeaza \: \: s - \frac{1}{3}s.[/tex]
coroana si 100 de puncte
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