Question

Aflati numarul natural N pentru care (3N+2) divizibil cu 5



Dau coroana!
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Answer 1

$5|(3n+2) \iff 3n+2 \in M_5=\{0,5,10,15,...,5k\}\\\\n \in {\{\frac{0-2}{3} ,\frac{5-2}{3} ,\frac{10-2}{3} ,\frac{15-2}{3} ,...,\frac{5k-2}{3} \}$

${n\in\{\frac{-2}{3} ,1,\frac{8}{3} ,\frac{13}{3} ,...,\frac{5k-2}{3} \} \ (1)$

$n \in \mathbb{N} \ (2)\\(1)(2) \implies \boxed{n =1}$