Question

Find a in a geometric series for which Sn = 728, r = 3 , and n = 6.

Answer 1

a = 2

Explanation:

In geometric series, Sum of the series formula :

Sn = a[(rⁿ - 1)/(r - 1)]

We are given that Sn = 728 and

r = 3 and n =6

Thus,plugging in the relevant values;

728 = a[(3^(6) - 1)/(3 - 1)]

728 = 364a

a = 728/364

a = 2