Can you help me factor 3x^3-4x^2-5x+2

I know it's suppose to either have a (x-2) or a (x+1) in it.

Look at the graph or use the rational roots theorem to find the roots at x = 2 and x = -1. Use the factor theorem to convert these roots into factors:
(x - 2) (x + 1)
Divide by the known factors:
(3x^3-4x^2-5x+2) / (((x - 2) (x + 1)) = 3x - 1
So altogether:
3x^3-4x^2-5x+2 = (x - 2) (x + 1) (3x - 1)