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