a z 3 + z 3 a + a 2 z 2 + z 2 a 2 + 2 z 2 − a z − z a − a 2 − 1 a 2 − 1 {\displaystyle az^{3}+{\frac {z^{3}}{a}}+a^{2}z^{2}+{\frac {z^{2}}{a^{2}}}+2z^{2}-az-{\frac {z}{a}}-a^{2}-{\frac {1}{a^{2}}}-1}
