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Re: [Q] Imposing resrictions on the roots?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg40490] Re: [Q] Imposing resrictions on the roots?
  • From: bobhanlon at aol.com (Bob Hanlon)
  • Date: Tue, 8 Apr 2003 03:02:42 -0400 (EDT)
  • References: <b6repr$7tg$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Needs["Algebra`InequalitySolve`"];

x /. Solve[a*x^2+b*x+c==0, x]

{(-b - Sqrt[b^2 - 4*a*c])/(2*a), (-b + Sqrt[b^2 - 4*a*c])/
   (2*a)}

InequalitySolve[#>=0, {a,b,c}]& /@ %

{a < 0 && (b <= 0 && c >= 0 || b > 0 && c >= b^2/(4*a)) || 
   a > 0 && (b < 0 && 0 <= c <= b^2/(4*a) || 
     b == 0 && c == 0), 
  a < 0 && (b == 0 && c == 0 || b > 0 && b^2/(4*a) <= c <= 
       0) || a > 0 && (b <= 0 && c <= b^2/(4*a) || 
     b > 0 && c <= 0)}


Bob Hanlon

In article <b6repr$7tg$1 at smc.vnet.net>, "Wonsuk Doh"
<wonsuk.doh at phd.bus.utexas.edu> wrote:

<< I have set up an equation and was able to obtain the analytical solutions
for it.
Is there any way I can get the conditions that make the root(s) have a
certain property? (e.g. non-negative real roots)
 >><BR><BR>


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