Finding: Axis of Symmetry & Vertex

Axis of Symmetry: is a line that cuts through a figure to create two sides as a mirrored image.

That line is the axis of symmetry.

Finding the axis of symmetry is commonly used in quadratic equations, to create parabolas.

~Axis of symmetry is fairly easy as long as one knows this formula.


*For example: y=x^2 + 6x+8

(a = 1, b = 6, c = 8)

-b/2a = -6/2(1) = -3

x = -3


Axis of Symmetry is x = -3
 Yay!











Vertex is the turning point of a parabola. Mainly the point where the parabola created its U-shape.

The Formulas one needs for a vertex would be...

     &

For example y = -x²+4x+1

a = -1, b = 4 , c = 1                               axis of Symmetry is x = 2.

x = -b/2a                                       


x = -4/2(-1)                                                          

x = 2

Now one would substitute x for 2 in the quadratic equation y = -x²+4x+1.

y = -x²+4x+1
y = -(2)² + 4(2) + 1
y = -4 + 8 + 1                                      Vertex is (2,5)
y = 5

Now x and y were found. :P