A generic argument that can be used to show that an álgebraalgebra is non-trivial is Bergman's Diamond LemmaBergman's Diamond Lemma. In this case, it immediately applies (there are no ambiguities) so for example $x$ is not in the ideal.
This method is useful even in situations in which you cannot find a representation to implement the idea in the other two answers, or when the characteristic gets in the way.