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caylus
Hello,

focus=(-4,-15)

If focus =(a,b) and directrix y=k
the parabola is:
y=1/(2(b-k)) * (x-a)²+(b+k)/2

So y=1/(2*(-15-3))*(x+4)²+(-15+3)/2
y=-(x+4)²/36 -6

Answer:

The required equation is [tex](x+4)^2=-36(y+6)[/tex].

Step-by-step explanation:

The standard form of the equation of the parabola is

[tex](x-h)^2=4p(y-k)[/tex]         .... (1)

where, (h, k) is vertex and  y = k - p is directrix.

It is given that vertex of parabola is (–4, –6) and the directrix is y = 3.

[tex](-4,-6)=(h,k)[/tex]

On comparing both the sides, we get

[tex]h=-4,k=-6[/tex]

Directrix of the parabola is

[tex]y=k-p[/tex]

Put y=3 and k=-6 in the above equation.

[tex]3=-6-p[/tex]

[tex]3+6=-p[/tex]

[tex]9=-p[/tex]

[tex]-9=p[/tex]

Substitute h=-4,p=-9 and k=-6 in equation (1).

[tex](x-(-4))^2=4(-9)(y-(-6))[/tex]

[tex](x+4)^2=-36(y+6)[/tex]

Therefore the required equation is [tex](x+4)^2=-36(y+6)[/tex].

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