Answer
The possible dimensions of the pedestal are $7x,\ 3x-2$ and $3x+2$.
Work Step by Step
$63x^{3}-28x=$
...factor out the GCF.
$=7x(9x^{2}-4)$
...write $9x^{2}-4$ as a difference of two squares.
$=7x(3x-2)(3x+2)$
The possible dimensions of the pedestal are $7x,\ 3x-2$ and $3x+2$.
