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Re: Does Mathematica think Sqrt[2] is rational?


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}}


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