− u 2 v 4 − 2 u 2 v 3 + 2 u 2 v 2 + 2 u v 3 − 3 u v 2 + 2 u v + 2 v 2 − 2 v + 1 u v 2 {\displaystyle -{\frac {u^{2}v^{4}-2u^{2}v^{3}+2u^{2}v^{2}+2uv^{3}-3uv^{2}+2uv+2v^{2}-2v+1}{uv^{2}}}}
