Question

Pentru oricare numar natural n , numarul S=2^n+3 +2^n+2+2^n+1+2^n se divide cu :
A) 9
B) 12
C) 13
D) 15
E) 18v

Answer 1

Răspuns:

2^n+3+2^n+2+2^n+1+2^n=

=2^n*2^3+2^n*2^2+2^n*2+2^n=

=2^n(8+4+2+1)=

=2^n*15 divizibil cu 15

R: D