Hitunglah jumlah deret geometri tak hingga 18+6+2+…!

Kelas 10 Matematika
Bab Barisan dan Deret Bilangan

r = U2/U1
r = 6/18
r = 1/3

S∞ = a/(1 – r)
S∞ = 18/(3/3 – 1/3)
S∞ = 18/(2/3)
S∞ = 18 . 3/2
S∞ = 27