What is an equation of a parabola with vertex at the origin and focus (0, 7)

a. y = -1/28 x^2

b. y = 1/28 x^2

c. x = -1/28 y^2

d. x = 1/28 y^2

Explanation:

p = focal distance = 7

the focal distance is from the vertex to the focus

The parabola opens upward (since the vertex is below the focus) so 'a' is positive and a = 1/(4p) = 1/(4*7) = 1/28

The vertex is (h,k) = (0,0)

Put this all together into the formula below and simplify

y = a(x-h)^2 + k

y = (1/28)(x - 0)^2 + 0

y = (1/28)x^2