z 4 a 8 + 3 z 2 a 8 + 2 a 8 − z 6 a 6 − 5 z 4 a 6 − 9 z 2 a 6 − 6 a 6 + 2 z 4 a 4 + 7 z 2 a 4 + 5 a 4 {\displaystyle z^{4}a^{8}+3z^{2}a^{8}+2a^{8}-z^{6}a^{6}-5z^{4}a^{6}-9z^{2}a^{6}-6a^{6}+2z^{4}a^{4}+7z^{2}a^{4}+5a^{4}}
