Master Theorem

atgofbhs

1. The problem statement, all variables and given/known data

i am trying to solve this but in vain...
i need some help or hints to solve the questions below


Show that case 3 of the master theorem is overstated, in the sense that the
regularity condition a · f(n/b) <= c · f(n) for some constant c < 1 implies
that there exists a constant e > 0 such that f(n) =
(nlogba+e).

2. Relevant equations

Given above

3. The attempt at a solution
I am trying to prove the reverse mathematically but not getting both the sides to same complexity