In the next picture, we can see the line x = -4 and the point (2, -1)
Given that the line is the axis of symmetry, then a point at the same distance of (2, -1) and the same y-coordinate must be located a the other side of the line. That point is (-10,1)
The distance between (2,1) and x = -4 is 6
The distance between (-10,1) and x = -4 is also 6
Then, (-10,1) is another point that lies on the graph of the parabola.
