Diketahui barisan geometri 1/2, 1/3, 2/9, ..., 32/729. Jika Un = 32/729, nilai n yang memenuhi adalah?.... A. 9 B. 8 C. 7 D. 6 E. 5 Tolong caranya sekalian, te

Kelas 8 Matematika
Bab Barisan dan Deret Bilangan

^ = pangkat

r = U2 : U1
r = 1/3 : 1/2
r = 1/3 . 2/1
r = 2/3

Un = 32/729
a . r^(n - 1) = 32/729
1/2 . (2/3)^(n - 1) = 32/729
(2/3)^(n - 1) = 32/729 . 2/1
(2/3)^(n - 1) = 64/729
(2/3)^(n - 1) = (2/3)^6
n - 1 = 6
n = 6 + 1
n = 7

✩✩ C ✩✩