Please explain every step and detail.

Solve the following recurrence relations using any of the following methods: unrolling, tail recursion, recurrence tree (include tree diagram), or expansion. Each case, show your work. (a) T(n) = T(n - 1) + 2^n if n > 1, and T(1) = 2 (b) T(n) = T(squareroot n) + 1 if n > 2, and T(n) = 0 otherwise