− ( t ( 2 ) t ( 1 ) 2 + 1 ) ( t ( 1 ) t ( 2 ) 2 + 1 ) t ( 1 ) 3 / 2 t ( 2 ) 3 / 2 {\displaystyle -{\frac {\left(t(2)t(1)^{2}+1\right)\left(t(1)t(2)^{2}+1\right)}{t(1)^{3/2}t(2)^{3/2}}}}
