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MathGroup Archive 2006

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Re: Re: Simplifying algebraic expressions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg66903] Re: [mg66877] Re: Simplifying algebraic expressions
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Sat, 3 Jun 2006 03:25:35 -0400 (EDT)
  • Organization: Mathematics & Statistics, Univ. of Mass./Amherst
  • References: <200606020809.EAA18060@smc.vnet.net>
  • Reply-to: murray at math.umass.edu
  • Sender: owner-wri-mathgroup at wolfram.com

I think the original poster's intention was to ask how to make 
Mathematica make the following simplifications:

   (-1)^(2 x + 3 y)
   ((-1)^(2x)) * ((-1)^(3y))
   (((-1)^2)^x) * ((-1)^(3y))
   (1^x) * (-1)^(3y)
   1 * (-1)^(3y)
   (-1)^(3y)

Of course this is valid only in special circumstances, even when x and y 
are real and positive.

Bill Rowe wrote:
> On 6/1/06 at 6:54 AM, aroy at cs.bc.edu (Amitabha Roy) wrote:
> 
>> I would like Mathematica to be able to take an expression, say,
> 
>> (-1)^{2 x  + 3 y} and be able to simplify to (-1)^y.
> 
>> Is there a way one can do this ?
> 
> I wonder if you really meant
> 
> (-1)^{2 x + 3 y}
> 
> instead of
> 
> (-1)^(2 x + 3 y)
> 
> in any case, the only way to simplify the 2 x + 3 y part to y would be to define x as -y. That is
> 
> (-1)^(2 x + 3 y)/.x->-y
> 
> will return (-1)^y
> 
> Or perhaps you wanted Mathematica to return (-1)^z where z is defined to be 2 x + 3 y? If so
> 
> (-1)^(2 x + 3 y) /. (-1)^(n_) :> (-1)^z
> 
> will return (-1)^z
> --
> To reply via email subtract one hundred and four
> 
> 

-- 
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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