You can
put this solution on YOUR website! Polynomial division should yield a remainder of 0. This works like regular long division.
x^2 x -6
----------------------------------------
|
3x-2 | 3x^3 x^2 -20x 12
| 3x^3 -2x^2
|________________
0 3x^2 -20x
3x^2 -2x
_________________
0 -18x 12
-18x 12
_______________
0 0