5. Describe how to determine the domain and range of a quadratic function when it is written in vertex form. What generalizations can you make?

Answer 1

y = a(x-h)^2+k
as with all polynomials, the domain is all real numbers.
Since the vertex is at (h,k), then
if a < 0, the range is y <= k
if a > 0, the range is y >= k
sketch a couple of parabolas to see why this is so.