Vertex: y = a (x-h) 2+k (a is not equal to 0), vertex (h, k)
Intersection point: y=a(x-x 1)(x-x2)(a is not equal to 0), where x 1 and x2 are abscissas of two intersecting x axes.
The shape of the image is related to | a |. As long as | a | is the same, the shapes of the two images are the same, but the positions are not necessarily the same.
As 1 asks, the quadratic coefficient of the same shape and different openings is a=2, and an analytical formula can be written by combining the vertex types.
y=2x^2-5
As asked in 2, because there is the highest point, the opening direction of the image is downward. When X >: 2, the image is downward, that is, the abscissa of the vertex is less than 2, so it is enough to take the vertex coordinates as (1, 2) and a=- 1, so the analytical formula can be written as y =-(x-/kloc-).