Question

Here is the problem that I'm having trouble with:

Rewrite each series in a sigma notation and find its sum.

1+.09+.81+...

I have no idea how I find the common difference or ratio in that one.

Answer 1

I don't think you will be able to do it with just those three terms.

Answer 2

perhaps you meant to type

1 + .09 + .0081 + ...

otherwise I agree with bob

If so, then

sum = [sigma] (.09)^(i-1) , i goes from 1 to infinity.

use S(infinity) = a/(1-r)