When I try to write the formal negation of that a relation is reflexive, with a positive sentence(no $\neg$ symbol), I don't really know what the "positive" negation of $x$ is in relation with $x$ is.
So the definition of reflexivity is this: $\forall x\in X:xRx$
1.) $\neg(\forall x\in X:xRx)$
2.) $\exists x\in X: \neg xRx$
And here I'm stuck.