Re: Re: can't MATHEMATICA simplify simple expressions?

• To: mathgroup at smc.vnet.net
• Subject: [mg51570] Re: [mg51514] Re: can't MATHEMATICA simplify simple expressions?
• From: Murray Eisenberg <murray at math.umass.edu>
• Date: Sat, 23 Oct 2004 00:21:57 -0400 (EDT)
• Organization: Mathematics & Statistics, Univ. of Mass./Amherst
• References: <cl4tg0\$8g7\$1@smc.vnet.net> <200410220220.WAA07117@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

But one should use PowerExpand with caution!  As the HelpBrowser entry says:

PowerExpand converts (a b)^c to a^c b^c, whatever the form of c is.
PowerExpand also converts (a^b)^c to a^(b c), whatever the form of
c is.
The transformations made by PowerExpand are correct in general only
if c is an integer or a and b are positive real numbers.

Jens-Peer Kuska wrote:
> Hi,
>
> a) because only for real vaules youn get a^3
> b) PowerExpand[(a^2)^(3/2) ] doesn what you want
>
> Regards
>   Jens
>
> "Cole Turner" <REMOVEcole.tuner at liwest.at> schrieb im Newsbeitrag
> news:cl4tg0\$8g7\$1 at smc.vnet.net...
>
>>if I enter:
>>
>>FullSimplify [ (a^2)^(3/2) ]
>>
>>(in correct MATHEMATICA syntax, the program does not yield the correct
>>result, a^3 ...
>>
>>why is that?

--
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305

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