Suku ke-n suatu barisan geometri adalah Un. Jika U1=k, U2=3k, U3 = 8k+4, maka U5 =

U2/U1 = U3/U2
3k/k = 8k+4/3k
3 = 8k +4/3k
9k = 8k +4
9k -8k = 4
k = 4

U1 = k = 4
U2 = 3k = 3.4 = 12
U3 = 8k+4 = 8(4)+4= 36
U4 = 36x 3 = 108
U5 = 108 x 3 = 324