For the first one, you could try dividing it by some possible roots, like -1, -4, or 3/2. Try dividing by (x+1), (x+4) or (2x-3). If it reduces to a quadratic by dividing by either of those, then you are in business.

You could also rewrite this one as

...............7x^2..........-7x

Factor:

For the second one, same logic as before. Try dividing this one by (x-3), x-2, or x+2. It should reduce to a quadratic and be easy thereafter. Okey-doke?.