Factor completely 6x^2 - 12x - 18 a. 6(x + 1) (x - 3) b. 6(x - 1) (x - 3) c. 3(2x + 3) (x - 1) d. (3x + 3) (3x - 3)

It's A. 
Glad i could help

To factor 6x^2 - 12x - 18, the absolute first thing you must do is to factor out any common factor from all three terms. In this case it is 6:

6x^2 - 12x - 18 = 6(x^2 - 2x - 3)

Now you must consider the factors of 1, the coefficient of the first term in the trinomial, and -3 the last term in the trinomial. 
1 = 1 x 1
-3 = 1 x -3, -1 x 3
Factoring is a guess and check procedure, but with time and practice it can come both easier and quicker. To factor you must find a combination of factors whose middle term will equal -2 when foiled. 

In this case it is: (x + 1)(x - 3)
the combinations were 1x1 and 1x-3.

Final A. 6(x+1)(x-3)