What's the Axis of Symmetry

The graph of a quadratic function is a parabola. The axis of symmetry of a parabola is a vertical line that divides the parabola into two congruent halves. The axis of symmetry always passes through the vertex of the parabola. The x - coordinate of the vertex is the equation of the axis of symmetry of the parabola.

The axis of symmetry is the line on a parabola which evenly splits the graph in half, you can find it by locating the vertex of the graph, it's usually in the middle