Answer:
23
y = ----- (x + 1)^2 - 3
9
Explanation:
Use the general vertex form equation of the parabola to find the function.
1) Vertex form equation: y = A (x - h)^2 + k
Where h and k are the vertex - coordinates, i.e. vertex = (h,k)
2) The vertex is the minimum (or maximum) of the parabola. In this case it is (-1,-3)
=> h = -1, k = -3.
3) Replace the vertex-coordinates in the vertex form equation of the parabola:
y = A(x + 1)^2 - 3
4) To find A replace the coordinates of the other point given: (2,20)
=> 20 = A(2 + 1)^2 - 3
=> A(3^2) = 20 + 3
=> A(9) = 23
=> A = 23/9
5) Replace h, k and A in the vertex form of the parabola:
y = (23/9) (x + 1)^2 - 3
