jika U5=1/8 dan U3=½. Tentukan S17?

ar⁴ = 1/8
ar² = 1/2

subtitusi ar² ke ar⁴
ar⁴ = 1/8
ar².r² = 1/8
1/2.r² = 1/8
r² = 1/8.2
r² = 1/4
r = √1/4
r = 1/2

ar² = 1/2
a.(1/2)² = 1/2
1/4.a = 1/2
a = 1/2.4
a = 2

S17 = a(1-r^n)/1-r
= 2(1-(1/2)^17)/1-1/2
= 2(1-(1/131072)/1/2
= 2(131071/131072)/1/2
= 131071/65536/1/2
= 2.131071/65536/1
= 262142/65536