Question

~p,~q |- ~(pVq)

Answer 1

you are new in the site, i guess!! Copy and paste the original problem, please. No one can help with your problem now. It is unclear and without any request

Answer 2

It just means that if I have ~P and ~Q true, then prove that ~(P V Q) is true

Answer 3

The easiest way is drawing the truth table.

Answer 4

I have to use Propositional logic,

Answer 5

Hint:
what you're trying to proof is the forward half of De Morgan's law in propositional logic.

Answer 6

You can proceed along the lines of the following:
\(\forall x \in (\lnot p \land \lnot q) \Rightarrow x\notin \lnot p \land x\notin \lnot q \Rightarrow x\notin (p \lor q) \)

Answer 7

\(\Rightarrow x\in \lnot (p\lor q)\)
I am not sure if this is entire rigorous, but that's the idea.

Answer 8

* entirely

Answer 9

I still think, unless specified otherwise, the truth table approach is the easiest.