Question

What is the sum of the geometric sequence 1, 3, 9, … if there are 14 terms?

Answer 1

okay, geometric sequences have to be like this:
a_2/a_1 = r & a_3/a_2 = r...... and so on

Answer 2

after you do that, you need to use this equation:

S_n = a_1(1-r^n)/(1-r)

Answer 3

r = 3 so:

S_14 = (1- 3^14)(1-3)
= -4782968/-2
= 2,391,484

Answer 4

hope that helps