The vertex-form of the equation of a parabola is
,
where (h, k) is the vertex point.
We are given that 9 is the maximum point, and that the axis of symmetry is the line x=-5.
The axis of symmetry passes through the vertex, so the x-coordinate of the vertex is -5. The maximum height is 9 means that the y-coordinate of the vertex is 9.
So: (h, k)=(-5, 9).
Substituting in the vertex-form, now we have:
.
We also know that (-7, 1) is a point of the parabola, so this point is an (x, y) which satisfies the equation. That is:
Now we have all the constants h, k and a, so we are able to write the equation:
.
Answer:
.