suma si diferenta de cuburi

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Andi Brojbeanu
Bernoulli
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Joined: Sun Mar 22, 2009 6:31 pm
Location: Targoviste (Dambovita)

suma si diferenta de cuburi

Post by Andi Brojbeanu »

Demonstrati ca numarul \( (1+2)^3+(3+4)^3+.......+(2n-1+2n)^3-1^3-2^3-3^3-4^3-.....-(2n-1)^3-(2n)^3 \) este multiplu de 18 pentru orice \( n\in \mathb{N}^* \).
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