diketahui barisan geometri 5,10,20,40....5120. tentukan suku tengahnya

Kelas 8 Matematika
Bab Barisan dan Deret Bilangan

5, 10, 20, 40, ..., 5.120

r = U2/U1
r = 10/5
r = 2

Un = 5.120
a . rⁿ⁻¹ = 5.120
5 . 2ⁿ⁻¹ = 5.120
2ⁿ⁻¹ = 5.120 / 5
2ⁿ⁻¹ = 1.024
2ⁿ⁻¹ = 2¹⁰
n - 1 = 10
n = 10 + 1
n = 11

Suku tengah = (U1 + U11)/2
Suku tengah = U6

U6 = a . r⁵
U6 = 5 . 2⁵
U6 = 5 . 32
U6 = 160