Show that $$Q[x]/(x^2-2)$$ is not isomorphic to $$Q[x]/(x^2-3)$$
I was practicing some exercises in Hungerford's abstract algebra book, I could make them all but this one. I think I have to verify if it is irreducible and thus be able to say if it is isomorphic, but I do not know how. I hope you can help me understand.