       Re: Simplify problems for checking easy equalities...

• To: mathgroup at smc.vnet.net
• Subject: [mg53872] Re: [mg53856] Simplify problems for checking easy equalities...
• From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
• Date: Tue, 1 Feb 2005 04:08:22 -0500 (EST)
• References: <200501300818.DAA08843@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

As I am sure many other will point out, the equality you want
Mathematica to prove only holds for certain values of x and n so it
would be wrong for it to give any other answer to the input you have
given it. However:

FullSimplify[Log[x^n] - n*Log[x],x>0&&Element[n,Reals]]

0

On 30 Jan 2005, at 08:18, Cyrus Erik Eierud wrote:

>
> Thanks for all great answers I've already found here!
> My problem is that I can not simplify what to me seems as a very
> simple equality task. This is what I want Mathematica to return zero
> for:
>
> in:= FullSimplify[Log[x^n] - n*Log[x]]
>
> out= -n Log[x] + Log[x^n])
>
> I have used Simplify to check equalities, but the one above (and many
> other equations similar to the one above) just don't simplify. Am I
> doing anything wrong or does anyone know of a better way to check
> equalities?
>
> Appreciate any help,
> Cyrus Eierud, Student
> cyruserik at tele2.se
>
>

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