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Re: Resolve a function

  • To: mathgroup at smc.vnet.net
  • Subject: [mg89706] Re: [mg89697] Resolve a function
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Wed, 18 Jun 2008 06:40:40 -0400 (EDT)
  • Reply-to: hanlonr at cox.net

f[r_] = 144/10*((2/Sqrt[r^2 + R^2]) - 1/r);

soln = Solve[f[r] == 0, r]

{{r -> -(R/Sqrt[3])}, {r -> R/Sqrt[3]}}

Simplify[f[r] /. soln, R > 0]

{(144*Sqrt[3])/(5*R), 0}

Simplify[f[r] /. soln, R < 0]

{0, -((144*Sqrt[3])/(5*R))}


---- maria <m.massaouti at windowslive.com> wrote: 
> Dear all,
> I am new with mathematica. I would be grateful if someone could tell
> me how can I find  the general solutions of the r for the following
> function f(r_) = 14.4* ((2/Sqrt[r^2 + R^2]) - 1/r )  (where
> R=constant). I just want to express the function as r =.....*f. Is
> this possible with mathematica.
> Thank you.
> 



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