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Re: Solution of this equation

  • To: mathgroup at
  • Subject: [mg20683] Re: Solution of this equation
  • From: "Kevin J. McCann" <kevin.mccann at>
  • Date: Sun, 7 Nov 1999 02:10:14 -0500
  • Organization: Johns Hopkins University Applied Physics Lab, Laurel, MD, USA
  • References: <7vrc3p$>
  • Sender: owner-wri-mathgroup at

When I Solve your equation I do get 3 answers.  Mathematica does not know
what Pr and Tr are so it can't know that the answers you desire are real.
If I plug in {Pr,Tr}={1,2} I get 3 solutions one of which is real.  What
values of these were you using?  Note that since your inputs are all exact,
mathematica is not returning approximate answers, i.e. since the
coefficients are all integers, you get exact answers.


Kevin J. McCann
Johns Hopkins University APL
Johns Hopkins Road
Laurel MD 20723-6099

Dave Richardson <dhr at> wrote in message
news:7vrc3p$2nd at
> Can anyone offer insight here?
> This Mathematica expression gives 3 solutions to the equation.
> Solve[Pr == (8*Tr)/(3*vr - 1) - 3/vr^2, vr]
> The problem is that there are 3 Real solutions, and Mathematica is giving
> solutions with (granted a small) imaginary component.
> And hitting it with  a full simplify is just not a good idea...
> Any help?
> Thanks,
> Dave!
> --
> Dave Richardson
> University of Maryland
> Department of Mechanical Engineering
> Center for Environmental Energy Engineering
> (301) 405-8726
> dhr at

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