Show that if is prime, then must be prime
Originally Posted by maximus101 Show that if is prime, then must be prime I recommend proving the "contrapositive". Assume p is NOT prime and show that is not prime.
It will help to use . You can't apply that to directly because, taking x= 2, x- 1= 2- 1= 1 so that's not a new factor.
Another related question, prove that 2^2k - 1 is divisible by 3 always.
Salahuddin Maths online