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2014-11-04T18:18:32+02:00
A=5^n*4^n(4^3 + 5*4^2 + 5^3 - 5^2*4)=
= 20^n(64+80+125-100)=20^n*169=20^n*13^2
 ⇒ 13| a pt ca a este multiplu al nr 13
2 5 2
2014-11-04T18:21:00+02:00
A=5^n*4^n(4^3 + 5*4^2 + 5^3 - 5^2*4)=
= 20^n(64+80+125-100)=20^n*169=20^n*13^2
 ⇒ 13| a pt ca a este multiplu al nr 13