Cormen Edition 3 Exercise 4.3 Question 3 (Page No. 87)

Question

We saw that the solution of $T(n) = T(\lceil n/2 \rceil) + n$ is $O(lg\ n)$. Show that the solution of this recurrence is also $\Omega(n\ lg\ n)$. Conclude that the solution is $\Theta(n\log \ n)$.