Re: Summations
- To: mathgroup at smc.vnet.net
- Subject: [mg78248] Re: Summations
- From: dh <dh at metrohm.ch>
- Date: Wed, 27 Jun 2007 05:17:56 -0400 (EDT)
- References: <f5qme1$46g$1@smc.vnet.net>
Hi Sima,
what problem do you have that you can not do it yourself?
Sum[i a^i,{i,1,n}] gives (a (1-a^n-a^n n+a^(1+n) n))/(-1+a)^2
Sum[i n^i+n^3,{i,1,m}] gives m n^3+(n (1-n^m-m n^m+m n^(1+m)))/(-1+n)^2
hope this helps, Daniel
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
>
>