Question

Using the recursive formula of a geometric sequence, find the first five sequences: An=An-1 • 2

Please explain how.

Answer 1

How: substitute the known value of An-1 to compute An. Repeat.

In order to do this, you need to know A0 or A1, which you have not given.

In terms of A1, the first 5 terms are
.. A1 = (needs to be given)
.. A2 = 2*A1
.. A3 = 2*A2 = 2*2*A1 = 4*A1
.. A4 = 2*A3 = 2*4*A1 = 8*A1
.. A5 = 2*A4 = 2*8*A1 = 16*A1

If you know A1, you can find the other 4 terms of the first 5 terms. If you don't know A1, this is the answer.