I know this is a duplicate but I had no idea what the other solution meant or how to go about approaching this problem. At first glance I thought about using Euclid's theorem that there are infinitely many primes and just doing proof by contradiction but I'm so confused right now. I'm horrible at math and I just want to understand how to approach this problem. I've tried proof by contradiction: Assume that there are only a finite number of primes in the form of $6n+5$. But I'm just completely lost on what to do after this.
The original question: How do you prove that there are infinitely many primes of the form $5 + 6n$?