Sums of Infinite series

Question

I am being asked to find the sum of each of the following two infinite series.  If a series does not have a sum, write "no sum" as the answer.

 

1.  1/2 + 1 + 2 + 4...

 

-- I think this has no sum as /r/ is >1

 

2.  9 - 3 + 1 -1/3 + 1/9 ...

 

-- I am getting like 27/4 with using the equation S= first term over 1-r

 

Please let me know if I am way off or on the right track.

Thanks!

Answer 1

You are very much on the right track.