Question

obtenha a soma dos 9 termos iniciais da pg. de 1° termo a1= 2 e razão q=4

Answer 1

Bom dia!

$\textup{a1}\rightarrow\textup{2}$
$\textup{N}\rightarrow\textup{9}$
$\textup{Q}\rightarrow\textup{4}$


$\textup{An}=\textup{a1}\times\textup{q}^{(n-1)}$
$\textup{A9}=\textup{2}\times4^{(9-1)}$
$\textup{A9}=\textup{2}\times4^{8}$
$\textup{A9}=\textup{2}\times65536$
$\textup{A9}=\boxed{131072}$



$\textup{Sn}=\frac{\textup{An}\times\textup{q}-\textup{A1}}{q-1}$

$\textup{S9}=\frac{\textup{131072}\times\textup{4}-\textup{2}}{4-1}$

$\textup{S9}=\frac{\textup{524288-2}}{3}$

$\textup{S9}=\frac{\textup{524286}}{3}$

$\textup{S9}=\boxed{174762}$



Att;Guilherme Lima