Answer:
the x-intercepts are (5, 0) and (-3, 0).
Explanation:
The standard equation of a vertical parabola with vertex at (h, k) is
y = a(x - h)^2 + k.
Here we are told that the vertex is at (1, -16), which means that h = 1 and y = -16. Thus, we have:
y = a(x - 1)^2 + (-16).
We are told also that the graph passes through (0, -15). Substituting -15 for y and 0 for x, we get:
-15 = a(0 - 1)^2 - 16, or
-15 = a - 16
Then a must be 1, and the equation of the parabola is
y = (x - 1)^2 - 16.
Now to find the x-intercepts: Set y = 0 and solve for x:
0 = (x - 1)^2 - 16, or
(x - 1)^2 = 16, or
x - 1 = ±√16 = ±4
Then x = 1 ± 4, or x = 5 or x = -3, so the x-intercepts are (5, 0) and (-3, 0).