But divides since . Therfore, since . There is a factor of and therefore it is congruent to 0 mod p.
.2. If gcd(a, 35)=1, show that a^12 = 1(mod 35)
The exponent of this group is .
Therefore for .
It is sufficient to prove,3. If p and q are distinct primes, prove that
p^(q-1) + q^(p-1) = 1 (mod pq)
Can you finish now?