Re: Newbie question: equations with sums.

• To: mathgroup at smc.vnet.net
• Subject: [mg92879] Re: [mg92856] Newbie question: equations with sums.
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Thu, 16 Oct 2008 05:06:53 -0400 (EDT)

```(Sum[i*f[i], {i, 0, -1 + n}] /. i -> k) ==
Sum[k*f[k], {k, 0, -1 + n}]

True

Bob Hanlon

---- Vend <vend82 at virgilio.it> wrote:

=============
Hello.

FullSimplify[\!\(
\*UnderoverscriptBox[\(\[Sum]\), \(i = 0\), \(\(-1\) + n\)]i\ f[
i]\) == \!\(
\*UnderoverscriptBox[\(\[Sum]\), \(k = 0\), \(\(-1\) + n\)]k\ f[k]\)]

Evaluates to:

\!\(
\*UnderoverscriptBox[\(\[Sum]\), \(i = 0\), \(\(-1\) + n\)]i\ f[
i]\) == \!\(
\*UnderoverscriptBox[\(\[Sum]\), \(k = 0\), \(\(-1\) + n\)]k\ f[k]\)

Why doesn't it evaluate to true? Is there a way to make the system
solve this kind of equations?

--

Bob Hanlon

```

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