What is the equation of the quadratic graph with a focus of (2, − 2) and a directrix of y = 0?

Verified Answer :

jbmow

f=(h,k+p) = (2,-2)
then           h = 2
and           -2= k + p
Directrix = 0 = k - p

Solve these 2 equations and 2 unknowns yields k=-1 and p=-1
The equation is therefore,
y=(1/4p)(x - 2)^2 -1

Answer:

The equation of the parabola is \((x-2)^2=-4(y+1)\).

Step-by-step explanation:

The standard form of the parabola is,

\((x-h)^2=4p(y-k)\)

Where, (h,k+p) is focus and directrix is y=k-p

It is given that the focus of (2,-2) and a directrix of y = 0

\((h,k+p)=(2,-2)\)

\(h=2\)

\(k+p= -2\)        ... (1)

Since directrix is y=0,

\(k-p=0\)           ... (2)

Add equation 1 and 2.

\(2k=-2\)

\(k=-1\)

Put this value in equation 2.

\(-1-p=0\)

\(p=-1\)

Now we have p= -1, k= -1and h=2.

The equation of the parabola is,

\((x-2)^2=4(-1)(y+1)\)

\((x-2)^2=-4(y+1)\)

Therefore the equation of the parabola is \((x-2)^2=-4(y+1)\).

View image DelcieRiveria