Question

Obtenha a soma dos 6 primeiros termos da P.G. (7, 14, ...)

Answer 1

$razao = \frac{a_{n+1}}{n}= \frac{14}{7}=2\\ \\\\S_n=\frac{a_1(q^n-1)}{q-1} \\\\S_6=\frac{7(2^6-1)}{2-1} \\\\S_6=\frac{7(64-1)}{1} \\\\S_6=7*63 \\\\S_6=441$