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MathGroup Archive 2006

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Re: Demostration

  • To: mathgroup at smc.vnet.net
  • Subject: [mg70446] Re: Demostration
  • From: Peter Pein <petsie at dordos.net>
  • Date: Mon, 16 Oct 2006 02:36:17 -0400 (EDT)
  • References: <egsdu4$cp1$1@smc.vnet.net>

Erickson Paul-CPTP18 schrieb:
> I guess this doesn't 'prove', but perhaps demonstrates:
> 
> 
> Select[ Range[-100000,200000], IntegerQ[Sqrt[#^3+9]] &]
> 
> {-2,0,3,6,40}
> 
> There are 5 x values within a reasonable range. The ten (fine pairs) are
> +/- due to the Sqrt for y.
> 
> 
> You might choice a smaller range in order for faster execution ;-)

You don't need to test for any integer x < -2, for example ;-)
> 
> 
> 
> 
> -----Original Message-----
> From: Miguel [mailto:mibelair at hotmail.com]
To: mathgroup at smc.vnet.net
> Subject: [mg70446]  Demostration
> 
> How canI to demostrate than the equation y^2=x^3+9 has 10 integer
> solutions?
> 
> 


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