principle root? problem

*To*: mathgroup at smc.vnet.net*Subject*: [mg32532] principle root? problem*From*: rdownes at aol.com (RDownes)*Date*: Fri, 25 Jan 2002 02:58:09 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

The other day, I was explaining something to a student regarding solving a simple algebra problem. (x^2-5)^(2/3)=16 The solution to which is easily found. All four that is! However my version of Mathematica only gave the two real. Is there a simple explanation for this? Also, Mathematica gives the solution to x^(1/2)= -16 as 256. Now, is this a "principle root" problem and are the two possibly related? Any insights would be appreciated for this little enigma. Thanks, Rob

**Follow-Ups**:**Re: principle root? problem***From:*Daniel Lichtblau <danl@wolfram.com>