Evaluate each of the integrals below. Assume that $a$ and $b$ are constants.

1. $\int(a^2) dx$ 

   Hint (a):

   Careful: '$a$' is NOT a variable.

2. $\int(bu^2 − a) du$ 

   Hint (b):

   The variable is '$u$'.

3. $\int(am − b) dm$ 

   Hint (c):

   You are integrating a straight line.