I have no clue how to do this problem and I have a math on Tuesday. My teacher is awful.
6x3-6 = 6(x3-1) = 6(x-1)(x2+x+1)
Another option is to use the cubic formula (like the quadratic formula, but for cases where you have a third degree polynomial like this one).
Google "cubic formula" and you'll find a lot of examples.
Good luck with your test!