Summing a Sequence: Finite or Infinite?

  • Thread starter Thread starter Firepanda
  • Start date Start date
  • Tags Tags
    Sequence
Firepanda
Messages
425
Reaction score
0
I've created two summations for my coursework, now I need to show whether or not the summations are finite or infinite.

The 2 summations are very similar:

2meqrl0.png


With the n/2 removed it was easy enough to show the sum was equal to 1 [edit: I now realize I may have this wrong], now with the n/2 term added I really have no idea where to start.

Any help appreciated, thanks.

Edit: I can see my writing may not be legible, 1's in the pic are straight vertical lines, some of the 2's may look like 1's, but they are 2's.
 
Last edited:
Physics news on Phys.org
Firepanda said:
I've created two summations for my coursework, now I need to show whether or not the summations are finite or infinite.

The 2 summations are very similar:

2meqrl0.png


With the n/2 removed it was easy enough to show the sum was equal to 1 [edit: I now realize I may have this wrong], now with the n/2 term added I really have no idea where to start.

Any help appreciated, thanks.

Edit: I can see my writing may not be legible, 1's in the pic are straight vertical lines, some of the 2's may look like 1's, but they are 2's.

For the first one, I found that the terms in the sequence approach a positive number. This is enough to convince me that the first series diverges.
 
Mark44 said:
For the first one, I found that the terms in the sequence approach a positive number. This is enough to convince me that the first series diverges.

Thanks for the reply!

Does this mean it sums to infinity?

What were your steps to find that it approaches a positive number?
 
Firepanda said:
Thanks for the reply!

Does this mean it sums to infinity?
Your textbook should have definitions for the terms converges and diverges.
Firepanda said:
What were your steps to find that it approaches a positive number?
I took the limit of the nth term in the sequence.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
Back
Top