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jtobin2003
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What is the equation of the quadratic graph with a focus of (1, 1) and a directrix of y = −1?

A) f(x) = −one fourth (x − 1)2 + 1
B) f(x) = −one fourth (x − 1)2
C) f(x) = one fourth (x − 1)2 + 1
D) f(x) = one fourth (x − 1)2

Answer :

Answer:

Answer is option D) y= [tex]\frac{1}{4}(x-1)^{2}[/tex]

Step-by-step explanation:

Quadratic graph with a focus and a directrix is a parabola as in the picture attached.

Now we assume a point (x,y) is given on the parabola.Focus of parabola be the point O(1,1) and the directrix y=(-1)

As we know that in a parabola distance OP is equal to the distance between P and directrix y=(-1)

Therefore OP = distance from directrix y = (-1)

[tex]\sqrt{(x-1)^{2}+(x-1)^{2}[/tex] = [tex]\sqrt{(y+1)^{2}[/tex]

[tex](x-1)^{2} +(y-1)^{2} = (y+1)^{2}[/tex]

[tex]y^{2}-2y+1+x^{2}-2x+1=y^{2}+2y+1[/tex]

[tex]1-2y+x^{2}-2x=2y[/tex]

[tex]1+x^{2}-2x=4y[/tex]

[tex]y=\frac{1}{4}(x-1)^{2}[/tex]

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