For Q5, Q7 use a direct proof, proof by contraposition or proof by contradiction. 5) Let a, b eZ+. Prove that (a/b+b/a) 22. 6) Prove that for every n ez, n? - 2 is not divisible by 4. 7) Let m, n20 be integers. Prove that if m un 259 then (m 2 30 or n > 30)