### What am I doing wrong with this function

I want to plot a function and its inverse.
I ~~issue
~~issue

F=plot ~~((2~~((2*(x^3-2)),-4,0)

G=plot(sign(0.5~~(x^3-2)),-4,0)
G=plot(sign(0.5~~x+2.0)~~x+2.0)~~*abs(0.5*x+2.0)^(1/3),-4,0)
abs(0.5*x+2.0)^(1/3),-4,0)

F+G

Now 2(x^3-2) is the inverse of (0.5x+2)^(1/3) (I even checked with a well known alternative to sage).

The plots come out with the scale of 2(x^3-2) all wrong. They should (obviously) be reflections in y=x.

Any help much appreciated