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Topic: closed form simplification
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Posts: 58
Registered: 12/6/04
closed form simplification
Posted: Nov 18, 1999 12:34 AM
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I'm not seeing this and it looks so obvious ...

here is the series I'm looking at:

sum {from i=1 to r} ip^i = p sum(i=1 to r)ip^(i-1)

now this RHS looks like p multiplied by the derivative of the LHS.
Can I use the identity 1+p+...+p^s = (1-p^(s+1))/(1-p) ? ...just
differentiate it once? If not what does this sum simplify to?

Thanks for the help,

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