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