The explicit formula for the sum of the geometric series is: Sn=[a(rⁿ-1)]/(r-1) where: a=first term n=number of terms r=common ratio From the series given: 5 + 25 + 125 + 625 + 3,125 + 15,625? a=5 r=5 n=6 thus the sum of the series will be: Sn=[5(5⁶-1)]/(5-1) Sn=(5(15625-1))/4 Sn=78120/4 Sn=19530
