The given function is
First, we find the vertex V(h,k), where
We know that a = -16 and b = 0, so
Then, we find k evaluating the function when x = 0.
The vertex is V(0, 40).
Then, we find the intercepts of the function when y = 0.
The intercepts are (-1.58, 0) and (1.58, 0).
Now, we use all three points to graph the function.
The image below shows the graph of the function:
In the image, we used t = x.