Show that $x^4+n(2-n)x^2+n^2$ reducible over Q for any natural number n.

Question

Show that $$x^4+n(2-n)x^2+n^2$$ reducible over Q for any natural number n.

Here is what I did $$x^4+n(2-n)x^2+n^2=x^4+2nx^2-n^2x^2+n^2=x^4+2nx^2+n^2-n^2x^2$$ $$=(x^2+n)^2-(nx)^2$$ $$=(x^2+n-nx)(x^2+n+nx)$$