Question

What are the first four terms of the geometric sequence an=2⋅an−1 and a1=3 ?

Responses

3, 5, 7, 9

3, 5, 7, 9

2, 6, 18, 54

2, 6, 18, 54

3, 6, 12, 24

3, 6, 12, 24

3, 4, 5, 6

Answer 1

The sequence is geometric with ratio 2. Starting at a1 = 3 gives:

a1 = 3, a2 = 2·3 = 6, a3 = 2·6 = 12, a4 = 2·12 = 24.

So the first four terms are 3, 6, 12, 24.