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