Question

1+2+$2^{2} +$2³ + .... + $2^{40}$

Answer 1

Este o progresie geometrica
b1=1
q=2
n=41
=> Sn= b1*(q^n - 1)/(q-1)
=> S41=1*(2^41 - 1)/1=@=2^41-1

Answer 2

S = 1+2+2^2+2^3+..............2^40
2S=2+2^2+2^3+2^4+..........2^41 le scadem
S-2S=1-2^41
S=2^41 - 1