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MathGroup Archive 2007

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Re: Summations

  • To: mathgroup at smc.vnet.net
  • Subject: [mg78273] Re: [mg78228] Summations
  • From: Curtis Osterhoudt <cfo at lanl.gov>
  • Date: Wed, 27 Jun 2007 05:30:45 -0400 (EDT)
  • Organization: LANL
  • References: <200706260833.EAA05727@smc.vnet.net>
  • Reply-to: cfo at lanl.gov

On Tuesday 26 June 2007 02:33:48 Sima wrote:
> Can someone please solve this summations:
>
> Summation(from i=1 to n) (i * a ^ i)
>
> Summation(from i=1 to m) (i * n ^ i + n ^ 3)
>
> you can mail me sollutions. Thanks

This looks suspiciously like a homework problem. Notice especially that once 
the first summation is done, the second one follows immediately and almost 
trivially from it. Googling the term "geometric series" might help immensely. 

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