Question

Write the equation of a parabola with a vertex at (-3, 7) and a directrix x = -8.

Answer 1

@tkhunny

Answer 2

With the vertex and directrix, the focus should be trivial. Where is it?

Answer 3

With the vertex and directrix, "p" should be trivial along with 4p. What is "p"?

Answer 4

wait jump ahead a couple of steps. is the equation \[y - 7 = \frac{ 1 }{ 20 }(x + 3)^{2}\]

Answer 5

No. That opens UP and you should be opening RIGHT. You do have p and the vertex.

Answer 6

so \[x + 3 = \frac{ 1 }{ 20 }(y - 7)^{2}\]

Answer 7

That's better. Do you believe it?

Answer 8

i think so.

Answer 9

You can ALWAYS check with the definition. With directrix at x = -8 and focus at (2,7), an application of the definition of a parabola should have the same result.

Good work.