# What is the axis of symmetry of the graph of y=x^2-3x+9?

$x = \frac{3}{2}$
the axis of symmetry of a parabola $y = a {x}^{2} + b x + c$ is given by $x = - \frac{b}{2} a$ (it's a vertical line), because $- \frac{b}{2} a$ is the $x$ of vertex of the parabola, and you know the axis is vertical and passes through the vertex, so you're done: $x = - \left(- \frac{3}{2}\right) \implies x = \frac{3}{2}$