derivations in predicate calculus

The problems:

a) for any

I'm confused about this one because I tried proof by contradiction, so:

(1) by assumption

(2) by assuming the negation of where is also written as

... and then isn't that already a contradiction?

b) where x is not free in

This one I think it must involve axioms 4 and 5 somehow, but I guess that's obvious

c) for any term not involving x

And this one must involve axioms 4 and 6

Derive them using these (for your convenience and my LaTeX practice):

Axioms:

1:

2:

3:

4: ( is a term freely substitutable for x in )

5: (where x is not free in )

6:

7:

As well as Modus Ponens, Generalization, and the Deduction theorem

Any help would be really appreciated!