Question

Determine a formula do termo geral de cada PG
a) (2,8, .....)
b) ( 3,9,...)
c) ( 2,1,...)

Answer 1

Formula do termo geral da PG: $a_{n} = a_{1} . q^{n-1}$

a) A1 = 2, q = 4 (porque 8/2 = 4), logo a resposta é:
$a_{n} = 2 . 4^{n-1}$

b) A1 = 3, q = 3 (porque 9/3 = 3), logo a resposta é:
$a_{n} = 3 . 3^{n-1}$

c) A1 = 1, q = 1/2 (porque 1/2 = 1/2), logo a resposta é:
$a_{n} = 1 . (\frac{1}{2})^{n-1}$