Please help me to understand this problem. I am confused

2.[35 Pts] Asymptotic Notation and Mathematical Induction: Use the definition of O, Q, and notation to prove that a. (5 points) Let f(n) = 0.02n2 + 20n. Show that f(n) = O(n2). b. (5 points) Let f(n) = O(n2) and g(n) = O(n2). Show that f(n) + g(n) = O(n2). c. (15 points) f(n) = 6n2 + 7n + 5 => O(n2), f(n)= 6n2 + 7n + 5 => Q(n2) and f(n)= 6n2 + 7n + 5 => O(n2) d. (10 points) Using mathematical induction to prove K 2 = n(n+1)(2n+1) k=1 6