7. Solve the following recurrences and find the efficiency class for each of them. 1. A(n) = 3A(n 1) for n > 1, A(1) = 4 2. A(n) = A(n 1) + 5 for n > 1, A(1) = 0 3. An) = An 1) + n for n > 0, AO) = 0 4. An) = An/5) + 1 for n > 1, A(1) = 1 (solve for n = 5k)