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Re: Cube root of -1 and 1

  • To: mathgroup at smc.vnet.net
  • Subject: [mg90903] Re: Cube root of -1 and 1
  • From: Narasimham <mathma18 at hotmail.com>
  • Date: Tue, 29 Jul 2008 01:37:37 -0400 (EDT)
  • References: <g6h5fm$h26$1@smc.vnet.net>

On Jul 27, 11:44 am, Bob F <deepyog... at gmail.com> wrote:
> Could someone explain why Mathematica evaluates these so differently?
>
> In[53]:=
>
> (Sqrt[36] - 7)^(1/3)
> (Sqrt[36] - 5)^(1/3)
>
> Out[53]= (-1)^(1/3)
>
> Out[54]= 1
>
> In other words why isn't (-1)^1/3 expressed as -1 ??
>
> Thanks...
>
> -Bob

After seeing responses of others, try to see rotating effect in cube
roots of 'another' unity:

( (1 + I )/Sqrt[2] ) ^ (1/3)

Narasimham




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