Question

determine o 8° termo da P.G (2,4,6...)​

Answer 1

Vamos começar calculando o valor da razão (q):

$razao~=~\frac{a_2}{a_1}\\\\\\razao~=~\frac{4}{2}\\\\\\\boxed{razao~=~2}$

Agora, utilizando a equação do termo geral da PG, temos:

$a_n~=~a_1~.~q^{n-1}\\\\\\a_8~=~a_1~.~q^{8-1}\\\\\\a_8~=~2~.~2^{7}\\\\\\a_8~=~2^{7+1}\\\\\\a_8~=~2^8\\\\\\\boxed{a_8~=~256}$

Answer 2

an = a1 .q^n-1

r = 4/2 = 2

n = 8

a1 = 2

Logo:

a8 = 2*2^8-1

a8 = 2*2^7

a8 = 2*128

a8 = 256

Dúvidas??Comente!!