Question

Encontre o número de termos da PG (1/5; 2/15;...; 128/10.935).

Answer 1

Bom dia Amaris

PG

u1 = 1/5
u2 = 2/15

razão

q = u2/u1 = (2/15)/(1/5) = (2/15)*(5/1) = 10/15 = 2/3

termo geral

un = u1*q^(n - 1)

(1/5) * (2/3)^(n - 1) = 128/10935

(2/3)^(n - 1) = (128*5)/10935 = 128/2187
(2/3)^(n - 1) = (2/3)^7 

n - 1 = 7

n = 8 termos