− z 8 a 12 − 8 z 6 a 12 − 21 z 4 a 12 − 20 z 2 a 12 − 5 a 12 + z 10 a 10 + 10 z 8 a 10 + 36 z 6 a 10 + 56 z 4 a 10 + 35 z 2 a 10 + 6 a 10 {\displaystyle -z^{8}a^{12}-8z^{6}a^{12}-21z^{4}a^{12}-20z^{2}a^{12}-5a^{12}+z^{10}a^{10}+10z^{8}a^{10}+36z^{6}a^{10}+56z^{4}a^{10}+35z^{2}a^{10}+6a^{10}}
