Some people may ask that when the Pythagorean School initially tried to confirm whether √2 is a rational number, they did not know that √2 is not a rational number. In this case, could you ask: √2 can be written in the form of the simplest fraction? The equivalent statement is, can p and q in √2= p/q be mutually prime?The author's answer is: you can't ask such a question. The reason is that, first of all, such a question is not the question under discussion at all, so it is unnecessary; Besides, even if we put aside the necessity of discussion and look at it in isolation, since the arguer still doesn't know whether √2 is a rational number, So, how ensure that this question will not be a complex question?