− 4 v u 3 + 4 u 3 + 8 v u 2 − 8 u 2 − 8 v u + 8 u + 4 v − 4 {\displaystyle -4vu^{3}+4u^{3}+8vu^{2}-8u^{2}-8vu+8u+4v-4}
