4. Prove the following equality holds on Zn with n2, for all a,b, and c in Zn a(bc)=(ab)(ac))) 5. Let a2mod6 and b3mod6. Prove or disprove: 27a2+4b20mod6 Use first principles, definitions, and theorems from class, or provide a counter example. 6. Let nN and n1. Give a proof by induction that 3(2n+2n1)