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MathGroup Archive 2004

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Re: Solve bug?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg52727] Re: [mg52705] Solve bug?
  • From: DrBob <drbob at bigfoot.com>
  • Date: Sat, 11 Dec 2004 05:21:23 -0500 (EST)
  • References: <200412100123.UAA18967@smc.vnet.net>
  • Reply-to: drbob at bigfoot.com
  • Sender: owner-wri-mathgroup at wolfram.com

Maybe you'll like the version 5.1 results:

c1 = (-50 + x)^2 + (-50 + y)^2 ==  156.25;
c2 = (-4.5 + x)^2 + (-56.25 + y)^2 == 156.25;
Solve[{c1, c2}]
{c1, c2} /. %
{{x -> 27.25 - 2.621453937237713*
       I, y -> 53.125 -
      19.08418466309055*I},
   {x -> 27.25 + 2.621453937237713*
       I, y -> 53.125 +
      19.08418466309055*I}}
{{True, True}, {True, True}}

Bobby

On Thu, 9 Dec 2004 20:23:46 -0500 (EST), <paul at selfreferral.com> wrote:

> Solve seems to be returning an invalid answer when I do this:
>
> c1 = (-50 + x)^2 + (-50 + y)^2 == 156.25
> c2 = (-4.5 + x)^2 + (-56.25 + y)^2 == 156.25
>
> Solve[{c1,c2}]
> {{x -> 16, y -> 43.75}, {x -> 84, y -> 43.75}}
>
> This answer is so wrong!!??
> Those two points are completely off. Not even close.
>
> c1 and c2 are the equations of two overlapping circles.
> Use ImplicitPlot to verify this fact.
> Why can't Mathematica resolve this simple sytem of equations correctly?
>
> If I am doing something wrong please tell me what it is.
>
> Also how can I cut and paste text from a mathematica notebook without
> getting all the slashes?
> Your help is greatly appreciated.
>
> Regards,
> Paul
>
>
>
>



-- 
DrBob at bigfoot.com
www.eclecticdreams.net


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