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