− v 2 u 4 + 3 v u 4 − 3 u 4 + 3 v 2 u 3 − 7 v u 3 + 4 u 3 − 4 v 2 u 2 + 7 v u 2 − 4 u 2 + 4 v 2 u − 7 v u + 3 u − 3 v 2 + 3 v − 1 {\displaystyle -v^{2}u^{4}+3vu^{4}-3u^{4}+3v^{2}u^{3}-7vu^{3}+4u^{3}-4v^{2}u^{2}+7vu^{2}-4u^{2}+4v^{2}u-7vu+3u-3v^{2}+3v-1}
