How to Find an Axis of Symmetry

Step-by-Step Guide

1. 1

   Step 1: Check the degree of your polynomial.

   The degree (or “order”) of a polynomial is simply the largest exponent value in the expression.
   
   If the degree of your polynomial is 2 (there is no exponent larger than x2), you can find the axis of symmetry using this method.
   
   If the degree of the polynomial is higher than 2, use Method
   2.
   
   To illustrate, take, as an example, the polynomial 2x2 + 3x –
   1.
   
   This highest exponent present is the x2, so it is a 2nd order polynomial, and you can use this first method to find the axis of symmetry.
2. 2

   Step 2: Plug your numbers into the axis of symmetry formula.

   To calculate the axis of symmetry for a 2nd order polynomial in the form ax2 + bx +c (a parabola), use the basic formula x =
   -b / 2a.
   
   In the example above, a = 2 b = 3, and c =
   -1.
   
   Insert these values into your formula, and you will get: x =
   -3 / 2(2) =
   -3/4. , The value you calculated with your axis of symmetry formula is the x-intercept of the axis of symmetry.
   
   In the example above, the axis of symmetry is
   -3/4.
3. 3

   Step 3: Write down the equation of the axis of symmetry.

Detailed Guide

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