Answer:
A
Step-by-step explanation:
Given a parabola in standard form
f(x) = ax² + bx + c ( a ≠ 0 )
then the x- coordinate of the vertex is
x = - [tex]\frac{b}{2a}[/tex]
f(x) = x² + 8x ← is in standard form
with a = 1 , b = 8 , then
x = - [tex]\frac{8}{2}[/tex] = - 4
substitute x = - 4 into f(x) for corresponding y- coordinate
f(- 4) = (- 4)² + 8(- 4) = 16 - 32 = - 16
vertex = (- 4, - 16 ) → A
