In each of the following, f: Z+ → R. Solve for fin) relative to the given set S, and determine the appropriate "big-Oh" form for / on S.
(a) f(1) = 5
f(n) = 4f(n/3) + 5, n = 3,9, 27, . ..
S = {3ʹ|I ∈ N]
(b) f(l) - 7
f(n) = f(n/5) + 7, n = 5, 25, 125, . . .
5 = {5ʹ|i ∈ N}