Answer:
x = - 4
Step-by-step explanation:
given a quadratic function in standard form
y = ax² + bx + c ( a ≠ 0 ) then the axis of symmetry is
x = - [tex]\frac{b}{2a}[/tex]
h(x) = 5x² + 40x + 64 ← is in standard form
with a = 5 , b = 40 , then axis of symmetry is
x = - [tex]\frac{40}{10}[/tex] = - 4
