Question

What is the axis of symmetry of h(x)=5x^2+40x+64

Answer 1

The axis of symmetry of a parabola is the vertical line passing through its vertex. Given a parabola $ax^2+bx+c=0$, the vertex x-coordinate can be found using

$x = -\dfrac{b}{2a}$

In your case, the formula leads to

$x = -\dfrac{40}{10} = -4$

So, this parabola is symmetric with respect to the line  $x = -4$