To find the inverse of the function f(x) = ln(x-1) for x > 1, set y = f(x). This leads to the equation y = ln(x-1), which can be rewritten as e^y = x - 1. Solving for x gives x = e^y + 1. Therefore, the inverse function is f^(-1)(y) = e^y + 1.
I just saw this one. If there are finitely many primes, then
##0<\prod_{p}\sin(\frac\pi p)=\prod_p\sin\left(\frac{\pi(1+2\prod_q q)}p\right)=0##
Of course it is in a way just a variation of Euclid's idea, but it is a one liner.