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