Let $P(x) : x^2 \leq 4$. The domain for $x$ is all positive integers. Determine truth values of the following propositions
(a) $P(1)$
(b) $\exists x \neg P(x)$
for (a)
I got $P(1)$ is the proposition $(1)^2 \leq 4$. Since $1<=4$ is true, it has a truth value T.
for (b)
I am unsure how to go about this. I started with creating an equivalency but got stuck.
$\exists x \neg P(x) \iff \neg[\forall x P(x)]$