Answer:
(3D +4)(D -2)
Step-by-step explanation:
The middle term needs to be split into two terms that sum to -2D and have a product of (3d²)(-8) = -24D². You know that -24 has the possible factorizations ...
-24 = -24·1 = -12·2 = -8·3 = -6·4
This last pair of factors has a sum of -2. So, the middle term of the original expression can be split into the two terms -6D and +4D.
3D² -2D -8 = 3D² -6D +4D -8
= 3D(D -2) +4(D -2)
= (3D +4)(D -2)
