Question

For y=a(x-h)^2 +k
Express the range in terms of k

Answer 1

If a >0, the range is
[k,∞)

If a<0, the range is
(−∞,k]

Answer 2

what are a, x, y , h , k each representing?

Answer 3

(h, k) represents the vertex.
The vertex is going to be either the HIGHEST or LOWEST point on the parabola.