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