Question

Which of the following represents a geometric series (remember what a series is as opposed to a sequence)?

Answer 1

The first answer is correct

Answer 2

Answer:

3 + 9 + 27 + ...

Step-by-step explanation:

3 + 9 + 15 + ... is not a geometric series because it has no common ratio.

$\frac{15}{9}\ne \frac{9}{3}$

3 + 9 + 27 + ... is a geometric series because there is a common ratio;

$r=\frac{27}{9}=\frac{9}{3}=3$

3, 9, 27, ... is a geometric sequence and not a series. The sum of all the  terms in a geometric sequence forms a geometric series.

3, 9, 15, ... is a not a geometric series.