Prove there is an irrational between any two rationals

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SUMMARY

The discussion centers on proving the existence of an irrational number between any two rational numbers, p and q, where p > q. The solution involves defining a positive real number e such that e < |p - q|, and utilizing the density of irrational numbers in the real numbers. By constructing a value x using the formula x = [(p + q)/2] + [(p - q)/2] * r/n, where r is any irrational and n is an integer, it is established that x lies within the interval (p, q) and is irrational.

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Homework Statement



Prove that there exists an irrational between any two rationals.



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The Attempt at a Solution



How would one do this? So far I've proven there is an irrational between any rational and irrational, any irrational and rational, that there's a rational between any two reals, or a irrational between any two reals in the attempt; I realize that it can be taken as a case of the last two; but I haven't been able to start with just p,q such that p>q, and p and q rational, and arrive at this result. It's pissing me off.

Thanks in advance.
 
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Let p ,q be rationals with p>q

Let e be a positive real. Then for e < |p-q|, q+e is in the open interval (p, q). Due to the density of the irrationals in R (as you pointed out, between any two reals is a rational), there is a positive irrational, call it a, that is less than e. Now take q+a. What can you say about that value?
 
Say the two rationals are p and q.
define
x=[(p+q)/2]+[(p-q)/2]r/n
where r is any irrational and n is any integer such that
|r|<n

show
(1/2)(p+q-|p-q|)<x<(1/2)(p+q+|p-q|)
or
|2x-p-q|<|p-q|
and
x is irrational
 
Last edited:

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