Question

Find the vertex of the given quadratic function.

Answer 1

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 = $\frac{4+8}{2}$ = 6

f(6) = (6 - 8 )(6 - 4 ) = -2 × 2 = - 4 ← y-coordinate

vertex = (6, - 4 ) → B