Re: Why is the negative root?
- To: mathgroup at smc.vnet.net
- Subject: [mg69491] Re: Why is the negative root?
- From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
- Date: Thu, 14 Sep 2006 06:55:22 -0400 (EDT)
- Organization: Uni Leipzig
- References: <ee8h8v$j48$1@smc.vnet.net>
Hi,
(Reduce[{z^3 - z^2 - b z - 1 == 0, b > 0, z > 0},
z] // ToRadicals) /.
b -> 3 // FullSimplify
gives
Sqrt[2]+z==1
And you should be more careful when you use // to
apply
functions and look in what order the functions are
used.
Regards
Jens
<p-valko at tamu.edu> schrieb im Newsbeitrag
news:ee8h8v$j48$1 at smc.vnet.net...
| (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
|