I’m factoring trinomials, plz? find gcf first

Factor 8 out of 16x^2 - 24x +8 

8 is the GFC

Factor the following:
16 x^2 - 24 x + 8

Factor 8 out of 16 x^2 - 24 x + 8:
8 (2 x^2 - 3 x + 1)
Factor the quadratic 2 x^2 - 3 x + 1. 
The coefficient of x^2 is 2 and the constant term is 1.
The product of 2 and 1 is 2. 
The factors of 2 which sum to -3 are -1 and -2.
So 2 x^2 - 3 x + 1 = 2 x^2 - 2 x - x + 1 = -(2 x - 1) + x (2 x - 1):
8 x (2 x - 1) - (2 x - 1)

Factor 2 x - 1 from x (2 x - 1) - (2 x - 1):
  8 (2 x - 1) (x - 1)

Horizontal change or the change of x