Factor each expression completely.

1. $x^2−49$ 

   Hint (a):

   Notice that this is the difference of squares.

2. $6x^2+48x$ 

   Hint (b):

   There are only 2 terms, so factor out the greatest common factor.

3. $x^2−x−72$ 

   Hint (c):

   Find two numbers that multiply to $−72$ and add to $−1$.

4. $2x^3−8x$ 

   Hint (d):

   Factor out the greatest common factor first, then see part (a).

   Answer (d):

   $2x(x+2)(x−2)$