− ( v − 1 ) ( w − 1 ) ( u w 2 − 2 u w + 2 u − 2 w 2 + 2 w − 1 ) u v w 3 / 2 {\displaystyle -{\frac {(v-1)(w-1)\left(uw^{2}-2uw+2u-2w^{2}+2w-1\right)}{{\sqrt {u}}{\sqrt {v}}w^{3/2}}}}