− v 2 u 4 + 2 v 2 u 3 − 2 v u 3 − 2 v 2 u 2 + 3 v u 2 − 2 u 2 − 2 v u + 2 u − 1 {\displaystyle -v^{2}u^{4}+2v^{2}u^{3}-2vu^{3}-2v^{2}u^{2}+3vu^{2}-2u^{2}-2vu+2u-1}
