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Re: Are some equations unsolvable?

• To: mathgroup at smc.vnet.net
• Subject: [mg128068] Re: Are some equations unsolvable?
• From: "Kevin J. McCann" <kjm at KevinMcCann.com>
• Date: Thu, 13 Sep 2012 03:38:44 -0400 (EDT)
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A quick look at your function indicates that you have Sqrt[Pi/(-1/(2 
sigma^2)))], which will give you an complex number for real sigma.

Kevin

On 9/12/2012 3:04 AM, Sergio Sergio wrote:
> Hi,
> This is what I have:
>
> f = (1/(sigma*Sqrt[2 Pi]))*Sqrt[(Pi/(-1/(2*sigma^2)))]*
>    Exp[((m/sigma^2)^2)/4*(-1/2*sigma^2) + (m^2/(2*sigma^2))]
>
> Solve[f == 216, sigma]
>
> And I get this message: "This system cannot be solved with the methods available to Solve"
>
> Is it because there is no way to isolate sigma? Or am I doing something wrong?
>
> Thanks
>