Answer:
The answer is B.
Step-by-step explanation:
Firstly, you have to elaborate the function :
[tex]f(x) = {x}^{2} - 4x - 12[/tex]
[tex]f(x) = {x}^{2} + 2x - 6x - 12[/tex]
Next you have to factorize by collecting like-terms :
[tex]f(x) = x(x + 2) - 6(x + 2)[/tex]
[tex]f(x) = (x - 6)(x + 2)[/tex]
Lastly, you can solve it by letting f(x) equals to zero :
[tex](x - 6)(x + 2) = 0[/tex]
[tex]x - 6 = 0[/tex]
[tex]x = 6[/tex]
[tex]x + 2 = 0[/tex]
[tex]x = - 2[/tex]
