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The focus of a parabola is (0, -3) and the directrix is y = 3. What is the equation of the parabola?
A.) y = 1/12 x^2
B.) y = -1/12 x^2
C.) x = -1/12 y^2
D.) x = 1/12 y^12

Please explain how you got your answer.

Respuesta :

Focus has coordinates (0, a)
a = -3
Thus, 4a = 4(-3) = -12

Because a is negative, we know it will be a concave down or concave left parabola. Hence, A and D can be eliminated. And we know it has to be B because the directrix is the horizontal line y = 3. Hence, the equation of the parabola becomes:

[tex]x^{2} = -12y[/tex] or [tex]y = -\frac{1}{12}x^{2}[/tex]

Answer:

x = -(1/12)y² is the real answer!!!!!

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