im confused because i wasnt sure if the step after (-2x)-3 would be 1/-8x3 or 3 root of -2x.

I remember my teacher talking about how -3 is 1/3 and 3 becomes the root but also at the same time I remember her doing a weird calculation

(-2x)^-3

= 1/(-2x)^2

= 1/[-2x(-2x)(-2x)]

= 1/[(-8)(x^3)]

=-1/(8 x^3)