Hello, I have questions regarding:

a) Let k be any integer. Prove that if k^3 is even, then k is even.

b) Prove that 3√2 is irrational. Hint: Mimic the proof that √2 is irrational and apply the result from part (a).

c) Suppose two numbers a and b are irrational. Must the sum a + b be irrational? Justify your answer with an appropriate proof or counterexample

Thanks for helping