5. Solve the following problems: 5a. By using proof by cases method, prove that "For all odd integers n, the number n? – 1 is divisible by 8." 5b. By using proof by contradiction technique, prove that...

Extracted text: 5. Solve the following problems: 5a. By using proof by cases method, prove that "For all odd integers n, the number n? – 1 is divisible by 8." 5b. By using proof by contradiction technique, prove that "For all integers n, if n? is even then n is even." 5c By using proof by contradiction technique, prove that "V2 is irrational."