Question

Find an explicit formula for the geometric sequence -9\,,-18\,,-36\,,-72,...

Answer 1

`f(x)=-9(2)^(^x^-^1^)`

Step-by-step explanation:

First, we find the common ratio by dividing any term by its previous term. We should do this a couple of times to make sure it's consistent. In this case, our common ratio is 2. Our first (or 1th) term of the sequence is -9, so our formula becomes

`f(x)=-9(2)^(^x^-^1^)`.