# focus of the parabola that has vertex (−3, 2),passes through the point (−10, 1).

• Apr 19th 2009, 01:51 PM
skylitejdm
focus 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 PM
skylitejdm
• Apr 19th 2009, 02:55 PM
skylitejdm
any hints?
• Apr 19th 2009, 03:13 PM
Reckoner
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 PM
stapel

Quote:

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

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)

Thank you! :D
• Apr 19th 2009, 03:21 PM
skylitejdm
Quote:

Originally Posted by Reckoner
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.

thank you for not letting me learn an equation like this and for not giving me the opportunity to give donation for people that can help me.... WOW is it a crime to get help from this forum? it that the whole purpose why they even made this forum!
• Apr 19th 2009, 03:29 PM
stapel
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 PM
masters
Quote:

Originally Posted by skylitejdm
thank you for not letting me learn an equation like this and for not giving me the opportunity to give donation for people that can help me.... WOW is it a crime to get help from this forum? it that the whole purpose why they even made this forum!