B
given f(x) in factored form, equate to zero for x-intercepts
(x - 8)(x - 4) = 0, hence
x = 4, x = 8 ← x- intercepts
The vertex lies on the axis of symmetry which is situated at the midpoint of the x- intercepts
x- coordinate of vertex = [tex]\frac{4+8}{2}[/tex] = 6
f(6) = (6 - 8 )(6 - 4 ) = -2 × 2 = - 4 ← y-coordinate
vertex = (6, - 4 ) → B
