# Axis of Symmetry $x=-\dfrac{b}{2a}$

The equation of the axis of symmetry of $y=ax^2+bx+c$ is $x=-\dfrac{b}{2a}$.

### Example 1

Find the equation of the axis of symmetry of $y=x^2+4x-2$.

### Example 2

Find the equation of the axis of symmetry of $y=-2x^2-12x+3$.

### Example 3

The equation of the axis of symmetry of $y=ax^2-(a+4)x-3$ is $x=1$. Find $a$.