Help with proving properties of Tails of Series

Hi, I have an issues with solving this problem.

Let the summation of a_{n} from n=1 to infinity be a series and let m be in the natural numbers. Show that the summation of a_{n} from n=1 to infinity converges IFF the summation of a_{m+n} from n=1 to infinity converges, and that (the summation of a_{n} from n=1 to infinity) = S_{m} + (the summation of a_{m+n} from n=1 to infinity converges).

I understand that this problem is basically telling you to prove the properties of the Tails of series, but I'm not sure how I would go about proving it. And sorry for all the long typing for all the summation things, I don't know how to type it out the proper way.

Re: Help with proving properties of Tails of Series

Well,

Now if , Then .

Since where k is a finite number(you are just adding up a finite number of terms so you get a finite number).

. So converges.

It should be pretty straightforward.

Re: Help with proving properties of Tails of Series

Hi thanks for responding. However, it says also to prove (the summation of an from n=1 to infinity) = Sm + (the summation of am+n from n=1 to infinity converges), which is basically what you wrote for the first line, so I feel like the answer you provided is incomplete. And sorry if this is a misguided response, but I'm still very lost in the whole field of real analysis still. so sorry and thank you.

Re: Help with proving properties of Tails of Series

Now i don't know how to be more clear than that, surely adding those two u get

Re: Help with proving properties of Tails of Series

Okay, Thank you. I get it now :).