If the equation is given in factored form and the roots are real, then you can identify the x-coordinate of the vertex by averaging the 2 root values. For example, if the roots are -2 and 5, the x-coord. of the vertex is (-2+5)/2, or 3/2.
Once you have this x value, subst. the value into the given equation to calculate y. Then write the vertex as (x,y).
