Online Course Discussion Forum
Math Challenge I-C #4.24
A parabola has a line of symmetry, which goes through the vertex. In this case the line of symmetry is the vertical line $x=8$, which means the vertex has $x$-coordinate $8$ and points equidistant to the line have the same $y$ coordinate. For example if the point $(4,10)$ is on the parabola, the point $(12,10)$ is also on the parabola, since $8 - 4 = 4$ and $8 + 4 = 12$.