Show that is false for all sets A, B and C using direct proof.

I'm not sure how to finish off my proof... can someone please help

If we were to prove that the statement is true then we would need to show that if then and if then

To formalise this we denote the following:

Let P(x) denote the proposition function "" and Q(x) denote the proposition function ""

Thus we need to show that and

Let us first focus on

Because we are using a direct proof let us assume the hypothesis P(x) is true. If we can show that Q(x) is false then the universally quantified statement is false and we have complete our proof.

Since P(x) is assumed to be true then can be interpreted as or .

is only true if:

1. is true and is true

2. is true and is false

3. is false and is true

Now Q(x) is interpreted as and

Now what...?