$T(1) = 1 , T(n) = 2T(n/2) + n^3$? Divide and conquer $T(1) = 1 , T(n) = 2T(n/2) + n^3$? Divide and conquer, need help, I dont know how to solve it?

Use Akra-Bazzi which is more useful than the Master Theorem.
Using Akra-Bazzi, I believe you get $$T(x) = \theta(x^3)$$
You can also use the Case 3 of Master theorem in the wiki link above. (Note: That also gives $\theta(x^3)$.)
