# Given y=x^2-5x+4, how do you write the equation of the axis of symmetry?

Nov 2, 2017

Axis of symmetry is $x = 2 \frac{1}{2}$

#### Explanation:

The equation given is that for a parabola because of the ${x}^{2}$ term.

A parabola has the standard form: $y = a {x}^{2} + b x + c$

Parabolas are always symmetrical about a vertical line called its axis of symmetry.

It will always have the equation $x = \ldots$ which indicates what the $x$-intercept is.

To find the axis of symmetry, use : $x = \frac{- b}{2 a}$

For this equation: $y = {x}^{2} - 5 x + 4$

$x = \frac{- \left(- 5\right)}{2 \left(1\right)}$

$x = \frac{5}{2} = 2 \frac{1}{2}$