Question 44025
Well, you've a good start!
{{{V = (6-2x)(8-2x)x}}}  Now continue by multiplying the three factors here to get the equation for the volume, v, in terms of x.

{{{V = 4x^3-28x^2+48x}}} Now you can graph this equation using a graphing calculator.  The graph looks like this:

{{{graph(300,200,-5,5,-10,25,4x^3-28x^2+48x)}}}

The valid range of x would be:
{{{0<x<3}}}
Because, if:{{{x<=0}}} or {{{x>=3}}} the volume would be zero or negative, and this is not meaningful.