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