Here’s the thing: you don’t need a ruler, a mirror, or a prayer. You just need one tiny formula.
It’s x = -b / (2a). That’s it. Memorize it. Tattoo it on your brain (not your arm, that’d be weird).
Where does it come from? It’s the x-coordinate of the vertex—the peak or valley of your parabola. And the axis of symmetry just lives right there.
