# Math Help - Primes and Euler phi-function

1. ## Primes and Euler phi-function

Let p and p+2 be twin primes. Prove that Euler phi-function(p+2)= Euler phi-function(p) +2.

2. $\phi(p) = p-1$ and $\phi(p+2) = (p+2)-1 = p+1$ since both $p$ and $p+2$ are prime.

so $\phi(p+2) = p+1 = (p-1)+2 = \phi(p)+2$.