Question

calcule a soma dos 20 primeiros termos da P.G (2,6,18,...)?

Answer 1

Sn=a1(q^n-1)/q-1                q=6/2=3
S20=2(3^20-1)/3-1
S20=2(3486784401-1)/2
S20=2(3486784400)/2
S20=3486784400