− ( u v − u + 1 ) ( u v − v + 1 ) ( u 2 v + u v 2 − u v + u + v ) u 2 v 2 {\displaystyle -{\frac {(uv-u+1)(uv-v+1)\left(u^{2}v+uv^{2}-uv+u+v\right)}{u^{2}v^{2}}}}
