Re: How to get an answer as a Root object?

• To: mathgroup at smc.vnet.net
• Subject: [mg57145] Re: How to get an answer as a Root object?
• From: "Valeri Astanoff" <astanoff at yahoo.fr>
• Date: Thu, 19 May 2005 03:08:12 -0400 (EDT)
• References: <d6bv8r\$pcu\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```The trouble is the derivative being infinite at the solution.
I use that trouble to find the solution :

In[1]:=f[s_]:=
(-1+Sqrt[2]-Sqrt[(1+2*Sqrt[2]-s)*(-1+s)]+s)*(-1-Sqrt[2]+Sqrt[2]*s-
Sqrt[-1-2*Sqrt[2]+2*(2+Sqrt[2]-s)*s])-(-1-Sqrt[2]+Sqrt[2]*s+
Sqrt[-1-2*Sqrt[2]+2*(2+Sqrt[2]-s)*s])*(-2-2*Sqrt[2]+2*s+2*

Sqrt[1-(1/4)*(-1-Sqrt[2]+Sqrt[(1+2*Sqrt[2]-s)*(-1+s)]+s)^2])

In[2]:=Select[s /. Solve[Numerator[Together[1/f'[s]]] == 0], 2 < # < 3
&] // Simplify

Out[2]= 2 + 1/Sqrt[2]

In[3]:= % // N

Out[3]= 2.70711

That's not what you asked for but that's all I can do!

v.a.

```

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