IMC 2008 ziua 2 problema 3

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Beniamin Bogosel
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IMC 2008 ziua 2 problema 3

Post by Beniamin Bogosel »

Fie \( n \) un numar natural nenul. Demonstrati ca
\( 2^{n-1}| \ \ \ \sum_{0\leq k<n/2}\left(\begin{array}n \\ 2k+1 \end{array}\right)5^k \).

IMC 2008
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Beniamin Bogosel
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Post by Beniamin Bogosel »

Indicatie: luam sirul \( a_n=\frac{(1+\sqrt{5})^n-(1-\sqrt{5})^n}{2sqrt{5}} \), acesta este chiar membrul drept. Se gaseste relatia de recurenta si problema e gata.
Yesterday is history,
Tomorow is a mistery,
But today is a gift.
That's why it's called present. :)

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