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MathGroup Archive 1999

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Re: simple Simplify[] question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg19789] Re: simple Simplify[] question
  • From: "Allan Hayes" <hay at haystack.demon.co.uk>
  • Date: Fri, 17 Sep 1999 01:36:44 -0400
  • References: <7rnkqn$emf@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Ulf Saalmann <us at atom.msi.se> wrote in message
news:7rnkqn$emf at smc.vnet.net...
>
>
>  Hello,
>
>  why gives Mathematica
>                                      2 3/2
>       Simplify[(a^2)^(3/2)]        (a )
>
>
>  and not
>                                       3
>                                     a
>
>  and how to convince Mathematica to do it?
>
>
>  Thanks
>          Ulf  (us at atom.msi.se)
>

Ulf,

Mathematica works with complex numbers; and  even with reals your reduction is not
always true:

Simplify[((-1)^2)^(3/2)]

1

(-1)^3

-1

However, we can tell Mathematica that a is positive, and then your reduction is true

Simplify[(a^2)^(3/2), a > 0]

a^3

Allan
---------------------
Allan Hayes
Mathematica Training and Consulting
Leicester UK
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565




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