Raymond B. answered • 01/27/21
Tutor
5
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Math, microeconomics or criminal justice
vertex is mid way between the directrix and focus: (4,-1/2)
y=a(x-4)^2 -1/2. Now plug in any point on the parabola to solve for a, the coefficient of the x^2 term
plug in (7,1) (7,1) is on the parabola because it is 3 units from the focus (7-4= 3) and 3 units from the directrix 1--2= 3. (7,1) is a point directly right of the focus
1 =a(3^2) - 1/2
9a = 3/2
a = 1/6
the parabola is
y=(1/6)(x-4)^2 -1/2 or to remove fractions multiply by 6
6y =x^2-8x +13
