Question

calcular a soma dos 7 primeiros termos da pg (7,14,28,...)

Answer 1

a1= 7 q= 2 n=7 an= ?

$an= a_{1} . q^{n-1}$

$an=1. 2^{6}$

an=1.64

an=64

$Sn= \frac{ a_{1}.( q^{n}-1) }{q-1}$

$Sn= \frac{7.( 2^{7}-1) }{2-1}$

$Sn= \frac{7.(128-1)}{1}$

Sn= 7.(127) 

Sn= 889

bons estudos !