sˈɪns ðə wˈeɪl ɡɹˈuːp ˈækts baɪ ɹᵻflˈɛkʃənz, ðeɪ ɑːɹ aɪsˈɑːmətɹiz ænd sˌoʊ ðə dᵻɡɹˈiː tˈuː pˌɑːlɪnˈoʊmɪəl ɪz wˈeɪlɪnvˈɛɹiənt.
Since the Weyl group acts by reflections, they are isometries and so the degree 2 polynomial  is Weyl-invariant.