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