Solve question number 1. a hint is given also. thank you

Anyway, for this assignment, below are what you have to complete. Do state, on the right, the rules that justify your steps, as always. 1. Show a proof by contradiction of [Hint: be careful about De Morgan, idempotency,... if any; yes, it is very easy to make mistakes in proofs] 2. Show a proof by contradiction of This is kind of obvious, but I want a formal proof by contradiction. Hint: as ahove, be carn, distriburivit. any] 3. Show a proof by contradiction of This is kind of obvious too, but I want a formal proof by contradiction