tentukan banyaknya suku dari barisan geometri 16,8,4,.......1/8

Bab Barisan dan Deret
Matematika SMP Kelas VIII

r = U2 : U1
r = 8 : 16
r = 1/2

Un = 1/8
a . rⁿ⁻¹ = 1/8
16 . (1/2)ⁿ⁻¹ = 1/8
(1/2)ⁿ⁻¹ = 1/8 . 1/16
(1/2)ⁿ⁻¹ = 1/128
(1/2)ⁿ⁻¹ = (1/2)⁷
n - 1 = 7
n = 7 + 1
n = 8