− ( u + v ) ( u 2 v + u v 2 − 2 u v + u + v ) u 3 / 2 v 3 / 2 {\displaystyle -{\frac {(u+v)\left(u^{2}v+uv^{2}-2uv+u+v\right)}{u^{3/2}v^{3/2}}}}
