carilah U8 pada barisan geometri berikut! a)7,14,28,56... b)9,3,1...

a)
a = 7
r = 14/7 = 2

U8 = ar^(n - 1)
U8 = 7(2)^(8 - 1)
U8 = 7(2)^7
U8 = 7(128)
U8 =896

b)
a = 9
r = 3/9 = 1/3

U8 = ar^(n - 1)
U8 = 9(1/3)^(8 - 1)
U8 = 9(1/3)^7
U8 = 9(1/2187)
U8 = 9/2187
U8 = 1/243