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 -- Paul Abbott Phone: +61 8 6488 2734 School of Physics, M013 Fax: +61 8 6488 1014 The University of Western Australia (CRICOS Provider No 00126G) 35 Stirling Highway Crawley WA 6009 mailto:paul at physics.uwa.edu.au AUSTRALIA http://physics.uwa.edu.au/~paul

**References**:**a simplification problem***From:*Hui Fang <fangh73@xmu.edu.cn>