the 42.5 gives you the x value that you want to put into your equation you should get 1256.25, if you have a graphing calc like the TI 84 it has tools on it where you do not have to do any math and it will locate the point on the graph
ok guys, I gotta graph p= -X^2 + 85X - 550
ive got this far,
P= f(x)
f(x)= -X^2 + 85X - 550
= Y = -X^2 +85X - 550
a= -1 b=85 c=-550
vertex(x) = -b/2a = -(85)/2(-1) = -85/-2 = 42.5
then i started to plug it into the Y vertex and something dosen't seem right
Sorry that I didnt get back to you sooner, your mistake is (-42.5)^2
What you need to do is -(42.5)^2+85(42.5)-550
what we have is a -1 being multipled by 42.5^2 so we need to keep that negative seperate,
if the equation said -2x^2+85x-550=y; you would keep that neg out right? we have to do the same thing with the negative 1, try and put then one there so you can see that after you square x then you need to multiple that be -1