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