For each of the following recursions, sketch a recursion tree and guess a good asymptotic upper bound on its solution. Then use the substitution method to verify your answer.

a)T(n) = T(n/2)+n^3

b)T(n) = 4T(n/3)+n

c)T(n) = 4T(n/2)+n

d)T(n) = 3T(n-1)+1