kan du 3*sqrt(8/27)
but that other stuf bout (-8/27) -(1/3) dont make sens
8/27=0.2962962962962296...
sqrt(0.296296...)=0.544433105395182
########## that other thang... maebee yu want (8/27)^ -(1/3)
(sumthun)^1/3...be the kube root
(sumthun)^-1/3=1/(kube root av sumthun)
kube root av negativ number...legal...anser=negativ