x^2 - 3x - 4x + 12 (you distribute x in (x-4) to each of the terms x and -3 and multiply them. x*x is x^2 and x*(-3) is -3x. Then, you distribute -4 in (x-4) to each of the terms x and -3 and multiply them. -4*x is -4x and -4*-3 is 12)
To complete the square we get the coefficient of x, divide it by 2 then square it. -3/4 divided by 2 = -3/8 and then squared it equals 9 / 64 answer is a
