Factor each quadratic completely.

1. $2 x ^ { 2 } - 2 x - 4$

   Hint (a):

   Start by factoring out the greatest common factor.

   Answer (a):

   $2(x−2)(x+1)$

2. $4 x ^ { 2 } - 24 x + 36$

   Hint (b):

   See the hint in part (a).