• To: mathgroup at smc.vnet.net
• From: JH <jlucio at ubu.es>
• Date: Fri, 5 Feb 2010 07:13:08 -0500 (EST)
• References: <hkgl3d\$6t8\$1@smc.vnet.net>

```I don't have any answer. I have tried several things:

FullSimplify[\!\(
\*UnderoverscriptBox[\(\[Sum]\), \(i = 1\), \(n\)]\(a[i]\)\) + \!\(
\*UnderoverscriptBox[\(\[Sum]\), \(i = 1 + n\), \(m\)]\(a[i]\)\),
n > 1 && m > n]

Solve[\!\(
\*UnderoverscriptBox[\(\[Sum]\), \(i = 1\), \(n\)]\(a[i]\)\) + \!\(
\*UnderoverscriptBox[\(\[Sum]\), \(i = 1 + n\), \(m\)]\(a[i]\)\) ==
x, x, n]

AND

Reduce[\!\(
\*UnderoverscriptBox[\(\[Sum]\), \(i = 1\), \(n\)]\(a[i]\)\) + \!\(
\*UnderoverscriptBox[\(\[Sum]\), \(i = 1 + n\), \(m\)]\(a[i]\)\) ==
x && m > n, x, Reals]

DON'T WORK, and I don't know why. Does anyone?

Other similar example is with definite integrals (Mathematica does no
simplification):

FullSimplify[\!\(
\*SubsuperscriptBox[\(\[Integral]\), \(a\), \(b\)]\(f[
x] \[DifferentialD]x\)\) + \!\(
\*SubsuperscriptBox[\(\[Integral]\), \(b\), \(c\)]\(f[
x] \[DifferentialD]x\)\), {x, f[x], a, b, c} \[Element] Reals]

AND THIS (?????)

FullSimplify[\!\(
\*SubsuperscriptBox[\(\[Integral]\), \(a\), \(b\)]\(f[
x] \[DifferentialD]x\)\) + \!\(
\*SubsuperscriptBox[\(\[Integral]\), \(b\), \(a\)]\(f[
x] \[DifferentialD]x\)\), {x, f[x], a, b, c} \[Element] Reals]

JH

```

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