(y - yo) = m.(x - xo)
We have the points (4, 12) and (x, 18) with slope of 3.
(18 - 12) = 3.(x - 4)
6 = 3x - 12
3x = 6 + 12
3x = 18
x = 18/3
x = 6
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 =
= 6
f(6) = (6 - 8 )(6 - 4 ) = -2 × 2 = - 4 ← y-coordinate
vertex = (6, - 4 ) → B