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MathGroup Archive 2005

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Re: a simplification problem

  • To: mathgroup at
  • Subject: [mg55224] Re: [mg55172] a simplification problem
  • From: Murray Eisenberg <murray at>
  • Date: Thu, 17 Mar 2005 03:28:49 -0500 (EST)
  • Organization: Mathematics & Statistics, Univ. of Mass./Amherst
  • References: <>
  • Reply-to: murray at
  • Sender: owner-wri-mathgroup at

(This sort of question keeps popping up in mathgroup.)

One answer is:


but that does NOT give you -1; rather it gives the principal cube root 
of -1, namely, 1/2 + (Sqrt[3]/2)I.

So there is no good reason that (-1)^(1/3) should simplify to -1.

Remember: Mathematica does not know you intended to form just real 
numbers here, so it wants to interpret such things in complex terms.

Hui Fang wrote:
> Dear All,
> My questions is simple:
> How do I simplify (-1)^(1/3) to -1?
> Thanks!

Murray Eisenberg                     murray at
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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