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