Re: Does Mathematica think Sqrt[2] is rational?
- To: mathgroup at smc.vnet.net
- Subject: [mg86678] Re: Does Mathematica think Sqrt[2] is rational?
- From: Bill Rowe <readnews at sbcglobal.net>
- Date: Tue, 18 Mar 2008 04:49:20 -0500 (EST)
On 3/17/08 at 12:22 AM, maderri2 at gmail.com (magma) wrote:
>expr2 = Exists[{x, y}, x^2 == 2 y^2]
>Mathematica correctly finds out that expr is true over the reals
>Reduce[expr2, {x, y}, Reals]
>But gives a wrong answer over the integers or the rationals
>Reduce[expr2, {x, y}, Integers]
>Reduce[expr2, {x, y}, Rationals]
I believe you are overlooking the trivial solution
In[5]:= Assuming[x \[Element] Integers && y \[Element] Integers,
FindInstance[expr2, {x, y}]]
Out[5]= {{x->0,y->0}}