Question

Aratati ca : a) 7|x unde x=2+2^2+2^3+...+2^108

Answer 1

Aratati ca : a) 7|x unde x=2+2^2+2^3+...+2^108

x=2+2^2+2^3+...+2^108

2+2²+2³=14 (M7)

2⁴+2⁵+2⁶=2³(2+2²+2³)

..... ........36 grupe de 3 numere

14+2³×14+2⁶×14+...+2¹⁰⁵×14=

7×2×(2³+2⁶+...+2¹⁰⁵)

x=(M7)

=>7lx