Question

Find the equation of a parabola with vertex(4,9)and y-intercept(0,-7?)
Can working out please be provided?

Answer 1

Assuming the axis of the parabola is vertical ....
Use the general equation and let the equation be

y = a(x-4)^2 + 9
but (0,-7) lies on it.
-7 = a(16) + 9
16a = -16
a = -1

<b>so y = -(x-4)^2 + 9</b>

or

Assume the axis if horizontal, let the equation be

x = k(y-9)^2 + 4
at (0,-7))
-7 = k(81) + 4
81k = -11
k = -11/81

so x = (-11/81)(y-9)^2 + 4