diket deret geometri 5+10+20+...+160,jumlah deret geometri tersebut adalah

Kelas 8 Matematika
Bab Barisan dan Deret Bilangan

^ = pangkat

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

Un = 160
a . r^(n - 1) = 160
5 . 2^(n - 1) = 160
2^(n - 1) = 160/5
2^(n - 1) = 32
2^(n - 1) = 2^5
n - 1 = 5
n = 5 + 1
n = 6

Sn = a . (rⁿ - 1) / (r - 1)
S6 = 5 . (2⁶ - 1) / (2 - 1)
S6 = 5 . (64 - 1) / 1
S6 = 5 . 63
S6 = 315