Answer:
All the intervals that contain the number
are solution of the problem
Step-by-step explanation:
we know that
The equation of a vertical parabola into vertex form is equal to

where
(h,k) is the vertex of the parabola
In this problem we have

Convert to vertex form


Group terms that contain the same variable, and move the constant to the opposite side of the equation

Complete the square. Remember to balance the equation by adding the same constants to each side.


Rewrite as perfect squares

-------> equation in vertex form
The vertex is the point 
The x-coordinate of the vertex is 