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by Scorpius
Sat Jan 10, 2009 4:47 pm
Forum: Combinatorica
Topic: Internet Olympiad Problema 7
Replies: 5
Views: 773

maxim bogdan wrote:Vrem sa demonstram ca in orice graf \( G=(V;E) \), cu \( |V|=7 \); \( |E|=7 \) exista un ciclu.

Se foloseste urmatoarea
Lema Daca \( G \) este un graf cu \( n \) varfuri in care nu exista un ciclu atunci \( |E|\leq n-1. \)
Poti sa demonstrezi lema?
by Scorpius
Sun Oct 26, 2008 8:48 pm
Forum: Inegalitati
Topic: Inegalitate simetrica non-standard
Replies: 1
Views: 1136

Iata cea mai simpla si cea mai naturala solutie: Din inegalitatea AM-GM se obtine ca: {(\sqrt{xy}+\sqrt{zt})+(\sqrt{xz}+\sqrt{yt})+(\sqrt{xt}+\sqrt{yz})\geq 3\sqrt[3]{(\sqrt{xy}+\sqrt{zt})(\sqrt{xz}+\sqrt{yt})(\sqrt{xt}+\sqrt{yz})}}= =3\sqrt[3]{xyz+yzt+ztx+txy+\sqrt{x^3yzt}+\sqrt{xy^3zt}+\sqrt{xyz^3...

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