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MathGroup Archive 2005

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Re: a simplification problem

  • To: mathgroup at smc.vnet.net
  • Subject: [mg55352] Re: a simplification problem
  • From: Paul Abbott <paul at physics.uwa.edu.au>
  • Date: Sun, 20 Mar 2005 04:11:45 -0500 (EST)
  • Organization: The University of Western Australia
  • References: <200503161035.FAA23728@smc.vnet.net> <d1bgl8$lpn$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

In article <d1bgl8$lpn$1 at smc.vnet.net>, DrBob <drbob at bigfoot.com> 
wrote:

> If you mean, "How do I extract the real third root of -1?", here's a method:
> 
> ComplexExpand[x /. Solve[x^3 == -1]]
> 
> {-1, 1/2 + (I*Sqrt[3])/2, 1/2 - (I*Sqrt[3])/2}
> 
> First@Select[%, FreeQ[#1, Complex] & ]
> 
> -1

To extract the real third root of -1, how about

  Root[#^3 + 1 & , 1]

Cheers,
Paul

-- 
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