How do u simplify -8sqrt2/2187 ?? I dont need decimal form, how do I keep it in radical form?

I will assume you mean this:   -8 sqrt(2187)

= -8 sqrt (81*27) = -8 (9) sqrt(27) = -72 sqrt (27) = -72 sqrt(9*3) = -72(3) sqrt (3) = - 216 sqrt3

$-8\sqrt{\frac{2}{2187}}$

=$\frac{-8\sqrt2}{27\sqrt3}$

=$-\frac{2^32^{\frac{1}{2}}}{3^33^{\frac{1}{2}}}$

=$-\frac{2^{\frac{7}{2}}}{3^{\frac{7}{2}}}$

$-(\frac{2}{3})^{\frac{7}{2}}$