Part a: factor x2c2 − 4xc2 − 21c2. show your work. (4 points)
part b: factor x2 + 6x + 9. show your work. (3 points)
part c: factor x2 − 9. show your work. (3 points)

Part A : x^2c^2 - 4xc^2 - 21c^2
             c^2(x^2 - 4x - 21)
             c^2(x - 7)(x + 3) <==

Part B : x^2 + 6x + 9
             (x + 3)(x + 3) or (x + 3)^2 <==

Part C : x^2 - 9
             (x + 3)(x - 3) <==

1603 is the correct one.