− a 4 z 10 + 2 a 6 z 8 − 6 a 4 z 8 + a 2 z 8 − a 8 z 6 + 10 a 6 z 6 − 15 a 4 z 6 + 4 a 2 z 6 − 4 a 8 z 4 + 19 a 6 z 4 − 20 a 4 z 4 + 6 a 2 z 4 − 5 a 8 z 2 + 17 a 6 z 2 − 12 a 4 z 2 + 5 a 2 z 2 − 3 a 8 + 5 a 6 − 2 a 4 + a 2 {\displaystyle -a^{4}z^{10}+2a^{6}z^{8}-6a^{4}z^{8}+a^{2}z^{8}-a^{8}z^{6}+10a^{6}z^{6}-15a^{4}z^{6}+4a^{2}z^{6}-4a^{8}z^{4}+19a^{6}z^{4}-20a^{4}z^{4}+6a^{2}z^{4}-5a^{8}z^{2}+17a^{6}z^{2}-12a^{4}z^{2}+5a^{2}z^{2}-3a^{8}+5a^{6}-2a^{4}+a^{2}}