Question

Cum se rezolva 2+2^2+2^3+...+2^2015

Answer 1

2015(2015+1) /2 =2015x2016/2=2015x1008=2031120

Answer 2

Se foloseste formula:
$2+2^2+2^3+...+2^n = 2(2^n-1) = 2^{n+1}-2$
Atunci 2+2^2+2^3+...+2^2015=2^2016-2