− v 2 u 4 + 2 v u 4 − u 4 + 5 v 2 u 3 − 10 v u 3 + 5 u 3 − 8 v 2 u 2 + 15 v u 2 − 8 u 2 + 5 v 2 u − 10 v u + 5 u − v 2 + 2 v − 1 {\displaystyle -v^{2}u^{4}+2vu^{4}-u^{4}+5v^{2}u^{3}-10vu^{3}+5u^{3}-8v^{2}u^{2}+15vu^{2}-8u^{2}+5v^{2}u-10vu+5u-v^{2}+2v-1}
