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Re: unwanted Complex result

• To: mathgroup at smc.vnet.net
• Subject: [mg91605] Re: unwanted Complex result
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Thu, 28 Aug 2008 07:41:05 -0400 (EDT)
• References: <g95k8a$543$1@smc.vnet.net>

Hi,

for a polynomial of 4. order there must not exist a real
zero and you have to modify the parameters in polynomial
to get real solutions.

Regards
   Jens

John Rivers wrote:
> Solve[
> (Sqrt[speed ^ 2 - windx ^ 2] + windy) / a speed ^ 2 + b speed + c ==
> distance / height
> , speed]
> 
> this works but returns 4 solutions that all return complex numbers
> 
> I need a real number
> 
> how do I:
> 
> - convert a complex result into real number
> or
> - solve the equation to give only real numbers
> 
>