Question

s=1+2^1+2^2+2^3+...+2^2017

Answer 1

s=2^0+2^1+...+2^2017
2s=2^1+2^2+...+2^2017+2^2018
*le scadem*
s=2^2018-2^0
s=2^2018-1.
Sper ca te am ajutat!:)

Answer 2

s=1+2^1+2^2+2^3+...+2^2017

este formula (nu stiu daca ati invatat-o la scoala):

1+2^1+2^2+.....2^n=2^(n+1)-1

s=2^(2017+1)-1=2^2018-1

fara formula:

2xs=2+2x2^1+2x2^2+......+2x2^2017=2+2^2+2^3+......+2^2017+2^2018

2xs-s=s=2^1+2^2+2^3+......+2^2017+2^2018-(1+2^1+2^2+2^3+...+2^2017)=

=2^2018-1