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Re: Equations system with zero

  • To: mathgroup at smc.vnet.net
  • Subject: [mg91374] Re: [mg91360] Equations system with zero
  • From: DrMajorBob <drmajorbob at att.net>
  • Date: Tue, 19 Aug 2008 07:13:55 -0400 (EDT)
  • References: <27595538.1219046810354.JavaMail.root@m08>
  • Reply-to: drmajorbob at longhorns.com

y/(9y) is undefined (meaningless) when y is zero.

End of story.

Bobby

On Mon, 18 Aug 2008 02:36:41 -0500, Miguel <mibelair at hotmail.com> wrote:

> Hi alll,
>
> Let the following equations system for x, y Reals
>
> Solve[{y/(9y)==0/(5x),x^2+3y^2},{x,y}]
> {}
>
> Mathematica 6.0.1 yields no solution. But the solutions exist. They
> are four solutions
>
> x=0, y=+-Sqrt[1/3]
> y=0, x=+-1
>
> Mathematica first simplifying y/(9y) -> 1/9 and it compare with 0/(5x) -
>> and yiels False and it stops the process. Is this correct?.
>
> In my opinion, the correct process would be
> (5*x*y)==(9*y*0)
> 5xy=0 ----> x=0 or y=0
>
> and substitution in the second equation.
>
>



-- 
DrMajorBob at longhorns.com


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