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Re: Equations system with zero

  • To: mathgroup at smc.vnet.net
  • Subject: [mg91384] Re: Equations system with zero
  • From: Bill Rowe <readnews at sbcglobal.net>
  • Date: Tue, 19 Aug 2008 07:15:45 -0400 (EDT)

On 8/18/08 at 3:36 AM, mibelair at hotmail.com (Miguel) wrote:

>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

None of these solve the problem as written. For any x, y not
equal to zero, the left hand side of the first equation
evaluates to a non-zero value and the right hand side evaluates
to 0. And if either x or y equal zero, as written one side or
the other evaluates to 0/0 which is undefined.

And if you fix this problem, Solve still will have a problem
since the second expression isn't an equation.


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