jumlah deret geometri tak hingga 36 + 9 + 9/4 + 9/16 +...adalah

jawab
a = 36
r = 9/36 = 1/4

s~ = a / ( 1 - r)
s~ = 36 / ( 1 - 1/4) = 36/ (3/4)
s~ = 4/3 x 36
s~ = 48