Tuesday, 6 October 2015

Examples of rsqrt2 as an irrational number, for real numbers $0



After I've read this question , and I tried some failed calculations, I've typed in Wolfram Alpha online calculator the code (sqrt(2)/2)^sqrt(2) to get as output that also this number is transcendent, and thus irrational.



Before this calculation with Wolfram Alpha, as I am saying was a curiosity that I was asking myself if it is possible deduce or are known some cases for which one can state that r2 is irrational, when $$02logr=logplogq.
taking logarithms. And additionally if we presume, by contradiction, that 2 is a rational number, I can write the condition PQlogr=logplogq,
where P and Q are positive integers satisfying gcd.




But (1) neither (2) don't say nothing to me.




Question. Imagine that a friend ask me for a reasoning to get examples of irrational numbers of the form r^{\sqrt{2}}, when the real number r runs on the set $0 what are simple requirements/conditions that need to be met those real numbers $0Thanks in advance.



Answer



The Gelfond-Schneider-theorem mentioned by Jack allows a more general choice for r :





For every algebraic irrational r with $0



A particular cute choice is the golden-ratio-number \phi=\frac{\sqrt{5}-1}{2}


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