Question

Pada suatu deret geometri, suku ke-3 = 40.000 , suku ke-5 = 400.000. tentukan suku ke-9!

Answer 1

U3 = ar^2
40000 = ar^2
a = 40000 / r^2
U5 = ar^4
400000 = ar^4
400000 = 40000/r^2 × r^4
10 = r ^2
10^4 = r^8
a = 4000
U9 = ar^8
U9 = 4000 10^4
U9 = 4 × 10^7

Answer 2

R⁴/r² = 400.000/40.000
   r² = 10
U3 = a.r² = 40.000
           a.10 = 40.000
                a = 40.000 / 10
                a = 4000

U9 = 4000 x 10⁶ = 4000.000.000