Re: unwanted Complex result

*To*: mathgroup at smc.vnet.net*Subject*: [mg91596] Re: [mg91589] unwanted Complex result*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Thu, 28 Aug 2008 07:39:27 -0400 (EDT)*Reply-to*: hanlonr at cox.net

soln = Solve[(Sqrt[speed^2 - windx^2] + windy)/a speed^2 + b speed + c == distance/height, speed]; Select[soln /. {windx -> 1, windy -> 1, a -> 1, b -> 1, c -> 1, distance -> 20, height -> 5} // N, FreeQ[#, Complex] &] {{speed->-1.46762},{speed->1.11901}} Bob Hanlon ---- John Rivers <first10 at btinternet.com> 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