# How do you determine if the vertex of y=x^2-2x-8 is a maximum or a minimum?

Nov 1, 2014

To determine if a quadratic equation's vertex is a max or a min,
check the coefficient of ${x}^{2}$

$y = a {x}^{2} + b x + c$

if $a$ is positive, the graph opens upward. so the vertex is a minimum

if $a$ is negative, the graph opens downward. so the vertex is a maximum.

In your equation $a = 1$. We can conclude that the vertex is a minimum.