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