Determine whether each of the following functions is (a) continuous, and (b) differentiable.

Answer
- This function is nice and smooth. It is both differentiable and continuous.
- This function is discontinuous therefore it isn't differentiable.
- This function is not differentiable at a because of the "point":

- This function is not continuous and therefore not differentiable at a:

- This function is not differentiable at a because of the "corner" there:
