Solve the following recurrence relations using master’s method.

(a)
\[
T(n) = 2T\left( \frac{n}{2} \right) + n^3, \quad n > 1
\]
\[
T(n) = 1, \quad n = 1
\]

(b)
\[
T(n) = 2T\left( \frac{n}{4} \right) + 1, \quad n > 1
\]
\[
T(n) = 1, \quad n = 1
\]