can someone pls solve this

4. (8.3)1 Using the Tree Method, solve (i.e., give the smallest Big- O estimate for) each of the following recurrence relations. Where possible, verify your answer using the Master Theorem. (a) T(n)=T(n/2)+O(n2) (b) T(n)=3T(n/3)+O(n) (c) T(n)=2T(n/3)+O(1) (d) T(n)=2T(n2)+O(1)