For (x-h)^2=4p(y-k) vertex is (h,k) distance from vertex to directix=p=distance from vertex to focus |4p|=focal width
remember, focus is on the side of the parabola where it opens and directix is at the back when p is negative, it opens down when p is positive, it opens up
look at equation -1/40(x-0)^2=(y-0) times -40 to both sides (x-0)^2=-40(y-0) (x-0)^2=4(-10)(y-0) vertex=(0,0) p=-10,it's negative so it opens down
focus is 10 units below vertex (y direction) focus=(0,-10)
diretix is 10 above directix is y=10
focal width=|4p|=|4(-10)|=|-40|=40
vertex=(0,0) focus=(0,-10) directix is y=10 focal width=40 units
Y = 8x + 40. Y = score, and x = hours of homework. Substitute 3 into x 8 x 3 = 24 24 + 40 = 64 So the model predicts a score of 64 for 3 hours of homework.