Hi can you teach me how to prove the following Big-Oh, Big- Omega and Big-theta question step by step with explanation? Thank you.

2. Determine whether the following statement is True or False. n(n+1)/2 = O(n) Answer: O True O False * Determine whether the following statement is True or False. 3. n(n+1)/2 = 0(n?) Answer: O True O False * Determine whether the following statement is True or False. 4. n(n+1)/2 = 0(n) Answer: O True O False