Quetion to find the equation of a parabola i want check

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SUMMARY

This discussion focuses on finding the equations of parabolas using the distance formula and the definition of a parabola. For part (a), with a directrix at x = -4 and a focus at (2, 2), the user incorrectly states y = -4, which does not align with the requirements. In part (b), the directrix at x = 2 indicates that the parabola should open horizontally, but the user's graph shows it opening upward, which is incorrect. The vertex must be calculated as the midpoint between the directrix and the focus.

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r-soy
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Hi all

Use the definition of a parabola and the distance formula to find the equation of a parabola with

a ) directix x = -4 and focus (2,2 )
B ) directix x = 2 and focus (6,-4 )

my answer :

383986876.jpg


206452772.jpg
 
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r-soy said:
Hi all

Use the definition of a parabola and the distance formula to find the equation of a parabola with

a ) directix x = -4 and focus (2,2 )
B ) directix x = 2 and focus (6,-4 )
Your work for a) is not consistent with the requirements above. In your work for a, you have y = -4. Which is it?

For b), because the directrix is x = 2, the parabola has to open to the left or right. Yours opens upward, which is wrong.

Also, you don't draw the directrix for either parabola in your graph. The vertex of the parabola is halfway between the directrix and focus, so you can use the directrix and focus to figure out where the vertex is.

r-soy said:
my answer :

383986876.jpg


206452772.jpg
 

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