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

a = 2

Step-by-step 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