# How do you write an explicit formula for this sequence: 2, -1, 1/2, -1/4, 1/8?

##### 1 Answer

Apr 30, 2016

This sequence is in GP

Since

The ratio of

The ratio of

The ratio of

and so on

So the sequence has 1st term 2

and common ratio

If 1st term of GP be A and common ratio is r then its nth term is given by

If we put a =2 , r =

If we put a =2 , r =

If we put a =2 , r =