Question

determine o numero de termos da P.G. (1, 2, 4,..., 256).

Answer 1

q = 4 → q = 2
      2
$a_{n}$ = $a_{1}$ . $q^{n - 1}$ → 256 = 1 . $2^{n - 1}$ → $2^{8}$ = 1 . $2^{n - 1}$ →
$2^{8}$ = $2^{n - 1}$ → 8 = n - 1 → 8 + 1 = n → n = 9

PG (1, 2, 4, 8, 16, 32, 64, 128, 256)

Answer 2

Fórmula: an = a1.q^(n-1)

an = 256
a1 = 1
n = ??
q = 2

256 = 1.2^(n-1)
256/1 = 2^(n-1)
256 = 2^(n-1)
2^8 = 2^(n-1)
8 = n - 1
8 + 1 = n
9 = n



Possui 9 termos.