Use the formal definition of Big-Oh to prove both parts of the question and show all work. Thanks in advance!

a. Use the formal definition of Big-Oh to prove that if f(n)- Vn4 - 4n3 6n2- 4n +1, then f(n)-O(n2 b. Use the formal definition of Big-Oh to prove that if f(n) 0(1000000). then f(n) = 0(1)