Question

Which of the following is the complete factorization of 3x2-6x-240?

Answer 1

1.  Reduce  3x2-6x-240   to    x^2 - 2x - 80

2.  Use " ^ " to indicate exponentiation

3.  Factor  x^2 - 2x - 80 using completing the square:

     x^2 - 2x + 1^2 - 1^2 - 80

         (x+1)^2 - 1  - 80
          (x+1)^2 - 81
          (x+1)^2 - 9^2  = (x+1-9)(x+1 +9), or (x-8)(x+10)

Final answer, with all factors shown:      3(x-8)(x+10)