Find the focus of the parabola that has vertex (−3, 2), opens horizontally, and passes through the point (−10, 1).

(−83/28, 2)(−87/28, 2) (−85/28, 2) (−4, 2)None of the above

- Apr 19th 2009, 01:51 PMskylitejdmfocus of the parabola that has vertex (−3, 2),passes through the point (−10, 1).
Find the focus of the parabola that has vertex (−3, 2), opens horizontally, and passes through the point (−10, 1).

(−83/28, 2)(−87/28, 2) (−85/28, 2) (−4, 2)None of the above - Apr 19th 2009, 02:37 PMskylitejdm
Help me out please

- Apr 19th 2009, 02:55 PMskylitejdm
any hints?

- Apr 19th 2009, 03:13 PMReckoner
For other members, please note that this is apparently an exam question (see here). I urge you not to encourage academic dishonesty by offering direct assistance on this problem.

- Apr 19th 2009, 03:17 PMstapel
I almost didn't view this thread, because your various replies made it look as though it had been answered already! (Blush)

To learn the basic process for finding the equation from some provided information, try**here**.

You know that the equation is something along the lines of 4p(x - h) = (y - k)^2, because the parabola opens horizontally instead of vertically.

You are given that (h, k) = (-3, 2). You are also given that the point (-10, 1) lies on the curve. Then:

. . . . .4p(x + 3) = (y - 2)^2

Plugging in the given point:

. . . . .4p(-10 + 3) = (1 - 2)^2

. . . . .4p(-7) = (-1)^2

. . . . .-28p = 1

. . . . .p = -1/28

Since p is negative, then the parabola opens to the left, with the vertex being on the right. To which side of the vertex, then, is the focus? How far is the focus from the vertex?

Then what are the coordinates of the focus? (Wink)

If you get stuck, please reply showing all of your work and reasoning so far.

Thank you! :D - Apr 19th 2009, 03:21 PMskylitejdm
- Apr 19th 2009, 03:29 PMstapel
Um... You might want to review those terms and conditions, etc. They're pretty explicit about wanting to aid learning, not facilitate cheating. (Wondering)

- Apr 19th 2009, 03:35 PMmasters
Read the Forum Rules:

10) Do not beg for answers. If your question is unanswered do not make a post begging for someone to reply back, it is totally useless. Other members can see the question.

20) MHF does not endorse academic dishonesty in any way. Do not attempt to get help with a take-home test, exam or anything of that nature. Certain teachers and professors allow help with general homework and some do not. Make sure you find out if you are allowed to receive help. Those caught cheating will not only be banned, but we will also do everything we can to report you to your academic institution. We have done so in the past and will do so again. - Apr 19th 2009, 03:41 PMskylitejdm
thanks for the advise... i turn the test in already... just trying to learn it now