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Bobianiculina
a fost răspuns

N=3n+2×5n+1-7×15n+1 divizibil cu 17

Răspuns :


[tex]\it N = 3^{n+2}\cdot5^{n+1} -7\cdot15^n+2\cdot15^{n+1} = \\\;\\ = 3^2\cdot3^n\cdot5\cdot5^n-7\cdot15^n+2\cdot15\cdot15^n = \\\;\\ 15^n(45-7+30) =15^n\cdot68 = 15^n\cdot4\cdot17\in M_{17} \Rightarrow N \vdots 17[/tex]