Every parabola has an axis of symmetry which is the line that runs down its 'center'. This line divides the graph into two perfect halves.
In the picture of on the left, the axis of symmetry is the line x = 1.
Explore how the graph and equation relate to the axis of symmetry, by using our interactive program below.
Identify Axis of Symmetry From Graph
It is the line x = 2
It is the line x = -1
Axis of Symmetry Formula
There are two different formulas that you can use to find the axis of symmetry. One formula works when the parabola's equation is in vertex form and the other works when the parabola's equation is in standard form.
If your equation is in standard form, then the formula for the axis of symmetry is:
x = -b/2a from the general standard form equation y = ax2+bx + c
Interactive Demonstration of Axis of Symmetry
Practice finding axis
of symmetry from Vertex Form Equation
finding axis of symmetry from Vertex Form Equation