Re: Why is the negative root?
- To: mathgroup at smc.vnet.net
- Subject: [mg69503] Re: [mg69474] Why is the negative root?
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Thu, 14 Sep 2006 06:56:11 -0400 (EDT)
- Reply-to: hanlonr at cox.net
Looks like a bug. Make the substition first
Clear[z];
z/.(Reduce[{z^3-z^2- b z-1==0/.b->3, z>0}, z]//ToRules)
1 + Sqrt[2]
Bob Hanlon
---- p-valko at tamu.edu wrote:
> (Reduce[{z^3-z^2- b z-1==0, b>0, z>0}, z] //ToRadicals)/.b->3.//Chop
>
> gives a negativ z:
>
> z == - 0.414214
>
> What am I doing wrong?
>
> Regards
> Peter
>
--
Bob Hanlon
hanlonr at cox.net