what is (-5/2)^3

The minus is raised to the neg 3 as well! but -1*-1*-1=-1 so it doesn't make any difference to the answer.

$${{\mathtt{\,-\,}}\left({\frac{{\mathtt{5}}}{{\mathtt{2}}}}\right)}^{{\mathtt{3}}} = {\mathtt{\,-\,}}{\frac{{\mathtt{125}}}{{\mathtt{8}}}} = -{\mathtt{15.625}}$$