Answer:
f(x) = x^2 + 16x + 56.
Step-by-step explanation:
The vertex form is:
y = a(x + 8)^2 - 8 where a is a constant.
When x = -6, y = 0 so:
0 = a (-6+8)^2 - 8
4^2a = 8
a = 1
So the function is y = (x + 8)^2 - 8
in standard form this is
y = x^2 + 16x + 64 - 8
y = x^2 + 16x + 56.
