Răspunsuri

  • Utilizator Brainly
2014-02-27T16:25:37+02:00
1+2+2^2+2^3+.....+2^2009=(1+2+2^2)+2^3(1+2+2^2)+2^6(1+2+2^2)+...+2^2007(1+2+2^2)=
7+7*2^3+7*2^6+....+7*2^2007=7(1+2^3+2^6+...+2^2007) ⇒ divizibil cu 7.
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