Question

demonstrati ca numarul a= 6 la puterea n, minus 1 este multiplu de 5

Answer 1

Se stie ca

$U_{6^n}=6\ \forall\ n\in N^*$

Deci

$U_{6^n-1}=5\ \forall\ n\ \in\ N$

Si de asemenea

$5| m\ \forall\ m\in N; U_m\in\{0;5\}$

Deci

$5|6^n-1\ \forall\ n\in N$