I'm a bit confused on how to apply contrapositives... This isn't for homework but I'm attempting to show that if n^2 + 2 is prime that 3|n. I'm wondering if this is an appropriate time for me to show the contrapositive of the statement to be true, therefore the original statement to be true. Contrapostive: if 3 does not divide n, then n^2+2 is not prime. I know how to show this contrapositive to be true... Am I doing this right?