berapa banyak suku barisan 1,3,9......,2187

jawab

pola  = 1, 3, 9, ..., 2187
a= 1
r = 3
un = arⁿ⁻¹
un = 3ⁿ⁻¹

3ⁿ⁻¹ = 2.187 = (3)⁷

 n -1 = 7
n  = 8