− v 2 u 4 + v u 4 + 2 v 2 u 3 − 4 v u 3 + u 3 − 3 v 2 u 2 + 5 v u 2 − 3 u 2 + v 2 u − 4 v u + 2 u + v − 1 {\displaystyle -v^{2}u^{4}+vu^{4}+2v^{2}u^{3}-4vu^{3}+u^{3}-3v^{2}u^{2}+5vu^{2}-3u^{2}+v^{2}u-4vu+2u+v-1}
