Thanks Leo!
2009/11/26 Leo Butler <l.butler at ed.ac.uk>
>
>
> On Thu, 26 Nov 2009, Julien Martin wrote:
>
> < Hello,
> < I am trying to solve the following equation:
> <
> < sum(4500*(1+r)^-i, i, 1, inf)=60000;
> < solve(%, r);
> <
> < And I only get a pair of empty brackets as a result...
> < Any clue?
> < Julien.
> <
> <
>
>
> Julien,
> You'll need to tell Maxima to simplify the sum:
>
> (%i2) sum(4500*(1+r)^-i, i, 1, inf)=60000,simpsum;
> Is abs(r+1)-1 positive, negative, or zero?
>
> p;
> (%o2) 4500/((r+1)*(1-1/(r+1))) = 60000
> (%i3) solve(%,r);
> (%o3) [r = 3/40]
>
> Leo
>
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>