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Re: Simplifying radicals

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  • Subject: [mg122292] Re: Simplifying radicals
  • From: Ray Koopman <koopman at>
  • Date: Sun, 23 Oct 2011 06:26:33 -0400 (EDT)
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  • References: <j7p1s8$5ko$>

On Oct 20, 4:49 am, Tom De Vries <tidetable... at> wrote:
> Hi,  I'm working with some introductory topics in radicals.
> I know that Mathematica assumes things about the domain used in
> problems,  so the principal cube root of a negative number will be
> complex... or something like that..
> I'm way down at the lower high school level simply working with cube
> roots of negative numbers and wanting a negative number result.
> I know there are ways of using assumptions and solving over the reals, etc.
> Is there any EASY way I can simply ask for the cube root of -729 and get -9?

qbrt = Piecewise[{{-(-#)^(1/3),#<0}},#^(1/3)]&

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