Exercise 2174Number theory › IrrationalityM1Added 3 Nov 2026
Irrationality of e+ π and πe
#irrationality#e#pi#open problem
Statement
Explain why it is unknown whether and are irrational.
Hint
If one of them were rational, then and would be roots of a quadratic, but no such relation is known.
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Solution
Known. and are both irrational (indeed transcendental).
If . Then are roots of where and . If both , then are algebraic — contradiction with transcendence.
But only one is known? Actually, if , then and are roots of for some . But we do not know is rational.
Open problem. Whether and are irrational is open. (However, at most one of them can be rational, since their sum and product being rational would force both to be algebraic.)
Conclusion. These are famous open problems in transcendence theory.