So, Jada, we need three factors, right?
The first thing we can factor out is 3x.
3x(x2 + 3x + 2)
We can then factor the trinomial into two binomials. Hopefully you know how to do that.
3x(x + 2)(x + 1)
So, our length, width and height are 3x, x + 2 and x + 1.
Hope this helps!