Question

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

Answer 1

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^n=2^(2015+1)-2 = 2^2016-2

Answer 2

   
$2+2^2+2^3+...+2^{2015} = \frac{2^{2016} -2 }{2-1} =2^{2016} -2$