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