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