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