5. The definition of a rational number is a number that can be written with the form a/b with the fraction a/b being in lowest form. For the purposes of this question, you do not whether V3 and V9 are rational numbers or not. Prove that v3v9 is an irrational number. You MUST include a lemma with your proof demonstrating that if (10 marks) a2 is divisible by 3 then a is divisible by 3. 6. Assume that a, b, and c are all odd integers. Prove that ax2 + bx + c cannot be 0. You will require lemmas (concerning the evenness or oddness of the sum or product of even and odd numbers) to complete this proof. You must include each of these (10 marks) lemmas in full. What is the power set of [0, 2,4)? List explicitly the members of the following sets. 7. (2 mark) 8. (2 marks each)