Diketahi baris geometri 2,4,8,16 dan seterusnya tentukanlah suku ke 11 dan suku ke 9 lagi

a = 2
r = 4/2 = 8/4 = 2

Un = ar^n-1

U11 = a • r^10
= 2 • (2)^10
= 2 • 1024
= 2.048

U9 = a • r^8
= 2 • (2)^8
= 2 • 256
= 512

Diket : a = 2
r = 2
Tanya : U11 ? U20 (11+9=20)?
Jawab: U11 = a×r^(n-1)
= 2 × 2^(11-1)
= 2 × 2^(10)
= 2 × 1024
= 2.048

U20 = a×r^(n-1)
= 2 × 2^(20-1)
= 2 × 2^(19)
= 2 × 524.288
= 1.048.576