Answer:
x = - 8
Step-by-step explanation:
The equation of a parabola in vertex form is
y = a(x - h)² + k
where (h, k) are the coordinates of the vertex and a is a multiplier
f(x) = 4(x + 8)² - 6 ← is in vertex form
with (h, k) = (- 8, - 6 )
The axis of symmetry is a vertical line passing through the vertex
with equation x = - 8
