Find the sum of the geometric sequence 3, 15, 75, 375, ... when there are 9 terms and select the correct answer below.

a. - 976,563

b. 976,563

c. 1,464,843

d. 976,562

c. 1,464,843

Step-by-step explanation:

The sum of n terms of a geometric sequence with first term a1 and common ratio r is given by ...

sn = a1 (r^n - 1) / (r - 1)

Filling in the values a1=3, r=5, n=9, we get ...

s9 = 3 (5^9 - 1) / (5 - 1) = 1,464,843