Question 1157013
{{{f(x)=x^2-2x-5}}}
You already see f contains a point  (0,-5).


Try completing the square.
{{{x^2-2x+1-5-1}}}
{{{(x^2-2x+1)-6}}}
{{{(x-1)^2-6}}}
Vertex is  (1,-6).


Directrix:
{{{4p=1}}}, the lead coefficient
{{{p=1/4}}}, distance of vertex from either focus or directrix
-
{{{y=-1/4}}}----------the Directrix



{{{graph(400,400,-10,10,-10,10,x^2-2x-5)}}}