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