Which formula describes the following geometric sequence? remember that n represents the term number.2, 6, 18, 54, a. an = 2 · 3n - 1 b. an = 3 · 2n - 1 c. an = 2 + 3(n - 1) d. an = 3 + 2(n - 1)

The given sequence is 2, 6, 18, 54, ...

Notice that this is a geometric sequence because here we have equal common ratio.

So, common ratio :

=

= 3

The formula for general term of a geometric sequence is,

Where, first term: a_{1} =2

Next step is to plug in these values in the above equation to get the formula for the given sequence.

Hence, the correct choice is A.

answer: i believe its b. if you sound out the sentences that sounds wrong.