Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2006
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2006

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Demostration

  • To: mathgroup at smc.vnet.net
  • Subject: [mg70453] Re: [mg70369] Demostration
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Mon, 16 Oct 2006 02:36:57 -0400 (EDT)
  • Reply-to: hanlonr at cox.net

Reduce[{y^2==x^3+9}, {x,y},Integers]

(x | y) â?? Integers && x >= -2 && 
  (y == -Sqrt[x^3 + 9] || y == Sqrt[x^3 + 9])

Select[Flatten[
    Table[{{x,-Sqrt[x^3+9]},{x,Sqrt[x^3+9]}},
      {x,-2,500}],1],
  IntegerQ[#[[2]]]&&#[[2]]^2==#[[1]]^3+9&]

{{-2, -1}, {-2, 1}, {0, -3}, {0, 3}, {3, -6}, {3, 6}, 
  {6, -15}, {6, 15}, {40, -253}, {40, 253}}

Length[%]

10


Bob Hanlon

---- Miguel <mibelair at hotmail.com> wrote: 
> How canI to demostrate than the equation y^2=x^3+9 has 10 integer
> solutions?
> 

--

Bob Hanlon
hanlonr at cox.net



  • Prev by Date: "Not a floating-point number" WHY?
  • Next by Date: Re: a fault in the Factor[] function for polynomials?
  • Previous by thread: RE: Demostration
  • Next by thread: Re: Demostration