− u 4 v 4 − u 4 v 3 − 2 u 3 v 4 + 5 u 3 v 3 − 4 u 3 v 2 + u 3 v + u 2 v 4 − 5 u 2 v 3 + 7 u 2 v 2 − 5 u 2 v + u 2 + u v 3 − 4 u v 2 + 5 u v − 2 u − v + 1 u 2 v 2 {\displaystyle -{\frac {u^{4}v^{4}-u^{4}v^{3}-2u^{3}v^{4}+5u^{3}v^{3}-4u^{3}v^{2}+u^{3}v+u^{2}v^{4}-5u^{2}v^{3}+7u^{2}v^{2}-5u^{2}v+u^{2}+uv^{3}-4uv^{2}+5uv-2u-v+1}{u^{2}v^{2}}}}