− a 12 + z 2 a 10 + a 10 + z 4 a 8 + 3 z 2 a 8 + a 8 − z 6 a 6 − 4 z 4 a 6 − 5 z 2 a 6 − 3 a 6 + 2 z 4 a 4 + 6 z 2 a 4 + 3 a 4 {\displaystyle -a^{12}+z^{2}a^{10}+a^{10}+z^{4}a^{8}+3z^{2}a^{8}+a^{8}-z^{6}a^{6}-4z^{4}a^{6}-5z^{2}a^{6}-3a^{6}+2z^{4}a^{4}+6z^{2}a^{4}+3a^{4}}