Jumlah deret geometri tak hingga: 1+1/3+1/9+1/27+1/81+1/243+......adalah

suku pertama a = 1, rasio r = 1/3
S tak hingga = a / (1 - r )
S~ = 1 / (1 - 1/3)
= 1 / (2/3)
= 3/2
= 1 1/2