discriminant is the type of root a quadratic has so you must fator in which this case is -6 + 6*8=48

which we divide 2 and it is 2(3x^2-3x+4) but as you can see nothing adds into -3 and multiples into 12 so these roots are deemed imaginary since it never croses the x-axis thus the discriminant is imaginary also if you do b^2-4ac you get a negative number which means that they are complex or imaginary roots