New posts in Rationality Testing

Proving the irrationality of the number $\cos\frac\pi9$

Is $(5+\sqrt[3]2)^n$ ever an integer for $n \in \Bbb Z \setminus \{0\}$?

Test of being a rational number for $(1-\frac13+\frac15-\frac17+\cdots)/(1+\frac14+\frac19+\frac1{16}+\cdots)$

Shorter proof of irrationality of $\sqrt{2}$?

Prove that $5^{1/3}+7^{1/2}$ is irrational

Proof that $\sqrt6 - \sqrt2 - \sqrt3$ is irrational.

What is the most unusual proof you know that $\sqrt{2}$ is irrational?

Homework 8th grader: $\pi^2$ is irrational

Are there any irrational numbers that have a difference of a rational number?

Proof that at most one of $e\pi$ and $e+\pi$ can be rational