a 12 − 4 z 2 a 10 − 5 a 10 + 5 z 4 a 8 + 12 z 2 a 8 + 8 a 8 − 2 z 6 a 6 − 7 z 4 a 6 − 11 z 2 a 6 − 7 a 6 + 3 z 4 a 4 + 7 z 2 a 4 + 4 a 4 {\displaystyle a^{12}-4z^{2}a^{10}-5a^{10}+5z^{4}a^{8}+12z^{2}a^{8}+8a^{8}-2z^{6}a^{6}-7z^{4}a^{6}-11z^{2}a^{6}-7a^{6}+3z^{4}a^{4}+7z^{2}a^{4}+4a^{4}}
