-b/(2a)，(4ac-b？ )/(4a))

For example, how about y=-3x? The vertex of -x+ 1

that is

a=-3，b=- 1，c= 1

-b/(2a)= 1/(-6)=- 1/6

(4ac-b？ )/(4a)=(- 12- 1)/(- 12)= 13/ 12

So the vertex (-1/6, 13/ 12)

Parabola passes through the origin y=ax? The vertex coordinates of +bx are (-b/2a, -b? /4a), that is, when c=0.