Find Quadratic Line of Symmetry

From Jennifer Ledwith

The axis of symmetry is also defined by the following equation:

x = -b/2a

Remember, a quadratic function has the following form:

y = ax² + bx + c

Follow 4 steps to use an equation to calculate the line of symmetry for y = x² + 2x

1. Identify a and b for y = 1x² + 2x. a = 1; b = 2
2. Plug into the equation x = -b/2a. x = -2/(2*1)
   
3. Simplify. x = -2/2
4. The line of symmetry is x = -1.

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• Find Quadratic Line of Symmetry
• Find the Line of Symmetry Graphically
• Use an Equation to Find the Line of Symmetry

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