Solve the following recurrence equations, using change of variables technique. Express your answer in terms of Theta(.) for T(n). Assume n = 2^k. For question 7a, find the explicit recurrence solution (find constants). For question 7b, only find the general recurrence solution. a. T(n) = 2T(n/2) + 3n, T(1) = 1 b. T(n) = 2T Squareroot n) + log(n)