− ( t ( 1 ) + t ( 2 ) ) ( t ( 2 ) 2 − t ( 2 ) + 1 ) 2 t ( 1 ) t ( 2 ) 5 / 2 {\displaystyle -{\frac {(t(1)+t(2))\left(t(2)^{2}-t(2)+1\right)^{2}}{{\sqrt {t(1)}}t(2)^{5/2}}}}
