First you must factor out a -4 giving you -8(2x^2-3x-4) then find what numbers multiply to equal -8 (you get that number by multiplying the leading coefficient 2 and the constant -2) and add to give you -3. Those numbers are -4 and 1. So the factored form of the original equation is -8(2x+1)(x-2) the reason why you have a -2 instead of -4 in the second parentheses is because when you multiply by the 2x in the first parentheses it will equal 4x. Hope this helps!