\(P(5)\) is the statement “\(3\cdot 5 + 1\) is even”, which is true. Thus the statement \(\exists x P(x)\) is true (for example, 5 is such an \(x\)). However, we cannot tell anything about \(\forall x P(x)\) since we do not know the truth value of \(P(x)\) for all elements of the domain of discourse. In this case, \(\forall x P(x)\) happens to be false (since \(P(4)\) is false, for example).
in-context