v u 4 − 3 v u 3 + u 3 − 2 v 2 u 2 + 3 v u 2 − 2 u 2 + v 2 u − 3 v u + v {\displaystyle vu^{4}-3vu^{3}+u^{3}-2v^{2}u^{2}+3vu^{2}-2u^{2}+v^{2}u-3vu+v}
