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