Please try to be as clear as possible, I know this question is already on chegg but I do not understand how they got to their solution.

3. Growth of Functions (11 points) (1) (4 points) Determine whether each of these functions is O(r2) (a) 100r 1000 (b) 10021000 (c) - 1000r2 (d) rlogr (2) (2 points) Use the definition of to show that 5n5+4n +3n3+2n2+ne (3) (2 points) Use the definition ore to show that 2n3-n + 10 (n*). (4) (3 points) Let f, g, h : N R+. Use the definition of big-Oh to prove that if f(n) E O(h(n) and g(n) E O(h(n)) then f(n) + g(n) O(h(n)). You should use different letters for the constants (i.e. don't use c to denote the constant for each big-Oh)