Assignment 5

1. Prove that: x {1, 2, 3, 4, 5}, 5x x2. Which proof method did you use?

2. Prove that: if a is any odd number and b is any even number, then a2 + b2 is odd.Which proof method did you use?

3. Prove that for all integers m, n and p, if m+n and n+p are odd integers, then m+p is an even integer. Which proof method did you use?

4. Prove or disprove that: real numbers a and b, if a2=b2 then a=b.