# show series is convergent or not by using subseries

• May 21st 2010, 01:38 PM
renlok
show series is convergent or not by using subseries
I have a question to show if the following series is convergent or not $\Sigma_{n \rightarrow 0}^{\inf} \frac{7^{n+1}}{8^n}$

and i have to show it with using different subseries most questions like this im ok with but with this im stumped would be very grateful for any help. Thanks.
• May 21st 2010, 01:41 PM
tonio
Quote:

Originally Posted by renlok
I have a question to show if the following series is convergent or not $\Sigma_{n \rightarrow 0}^{\inf} \frac{7^{n+1}}{8^n}$

and i have to show it with using different subseries most questions like this im ok with but with this im stumped would be very grateful for any help. Thanks.

What do you mean "by subseries"?? The series is clearly convergent: $\sum^\infty_{n=0}\frac{7^{n+1}}{8}=7\sum^\infty_{n =1}\left(\frac{7}{8}\right)^n$ , but what is "by subseries"...?

Tonio
• May 23rd 2010, 12:52 AM
Idealconvergence
explain precisely
It will better to explain the problem you want to solve more precisely. Are you trying comparison test?