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