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calculati ultima cifra
5 la puterea 7+6 la puterea 2005+11la puterea 2004


Răspuns :

5^2005+6^2005+11^2004=5^7+6^2005+5^2004+6^2004=5^2004(5+1)+6^2004(6+1)=6*5^2004 +7* 6^2004
U=2

U(5^7)+U(6^2005)+U(11^2004)=U(5+6+1)=U(12)=2
 Obs. 5 la orice putere are ultima cifra 5
         6  la orice putere are ultima cifra 6
         1  la orice putere  este 1