The answer is (3d+2) (3d+2).
Steps:
Break the expression into groups:
(9d^2+6d)+(6d+4)
Factor out 3d from 9d^2+6d:
3d(3d+2)
Factor out 2 from 6d and 4: 2(3d+2)
=3d(3d+2)+2(3d+2)
Factor out common term (3d+2)
=(3d+2)(3d+2)
Hope this helps you! (:
-PsychoChicken4040