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        riddles >> easy >> Evaluate Sum
        
(Message started by: Benny on Mar 17^th, 2012, 9:59am)

Title: Evaluate Sum
Post by Benny on Mar 17^th, 2012, 9:59am

n=1 to infinity SUM (48n)/(n^4+4)

= 12/(n^2 - 2n+2) - 12/(n^2 + 2n+2)

Title: Re: Evaluate Sum
Post by pex on Mar 17^th, 2012, 1:18pm

on 03/17/12 at 09:59:33, Benny wrote:

n=1 to infinity SUM (48n)/(n^4+4)

= 12/(n^2 - 2n+2) - 12/(n^2 + 2n+2)

It's [hide]... eighteen ...[/hide]

Hint: [hide]Complete the squares in the denominators of your last expression, and telescope.[/hide]

Title: Re: Evaluate Sum
Post by Benny on Mar 20^th, 2012, 11:17am

Thanks. I don't know how I missed that.