Question

What is the equation of the following graph?

Answer 1

y=-a(x-h)²+k

the origin is vertex, so:
y=-ax²

now, we need to use one point to solve for a
-3=-a(8)²
-3=-64a
3/64=a

So it seems as though the graph is y=-(3/64)x²
https://www.desmos.com/calculator/9czngjovrh