Examples 6, 7 and 8 are all very helpful
a.) This is irreducible over Q by Eisenstein with p=3. Eisenstein states that if a number divides every co-efficient but the first then it is irreducible. And 3 divides 9, 12, and 6.
c.) This is done the exact same way as a.)
e.) Multiply all co-efficients by 14 and then use Eisenstein with p=3.
-Zach Simpson