Question 64480
The easiest way to find the vertex of f(x)= ax^2 + bx + c is {{{x=-b/(2a) }}}
In this case, {{{x = -(-8)/(2*1) = 4}}}



To find the y coordinate of the vertex, "Plug it in, plug it in!":
{{{y = x^2-8x-20}}}
{{{y=4^2 -8*4-20= -36}}}
Vertex = (4, -36)

Y intercept is always where x=0, so y = -20.  

{{{graph (300,600, -4, 12, -40, 40, x^2 -8x-20) }}}


R^2 at SCC