what is 4^3/2

When raising a number to the power of a fraction, the numberator of the fraction becomes your new exponet, and the demoninator becomes your root.

I assume you mean the square root of 4^3:

sqrt(4^3) =

sqrt(4*4*4) =

sqrt(16*4) =

sqrt(64) =

$$\mathbf{\pm\;8.}$$