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anonymous
 one year ago
Find the standard form of the equation of the parabola with a focus at (4, 0) and a directrix at x = 4.
Could someone please help?
anonymous
 one year ago
Find the standard form of the equation of the parabola with a focus at (4, 0) and a directrix at x = 4. Could someone please help?

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wintersuntime
 one year ago
Best ResponseYou've already chosen the best response.0Write an equation for the parabola with focus (4,0) and directrix y=2. Thanks! .. Standard form of parabola: (xh)^2=4p(yk), with (h,k) being the (x,y) coordinates of the vertex Given parabola opens downward with axis of symmetry at x=4. Vertex at (4,1). p=1 Equation of parabola: (x4)^2=4(y1) (ans) see the graph below as a visual check on the answer .. y=1(x4)^2/4

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I'm so confused I'm sorry @wintersuntime

wintersuntime
 one year ago
Best ResponseYou've already chosen the best response.0Are you trying to graph it ?

wintersuntime
 one year ago
Best ResponseYou've already chosen the best response.0And it's okay I love helping others

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0No. These are the answer I am given: A. y^2 = 8x B. 16y = x^2 C. y = 1/16x^2 D. x = 1/16y^2

wintersuntime
 one year ago
Best ResponseYou've already chosen the best response.0What do you think the answer will be ?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I am thinking C. @wintersuntime

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Honestly, I'm not sure. I just thought that standard form looked most similar to that choice. @wintersuntime

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Could you explain how to find the correct answer then? I am so lost. @saseal

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0dw:1438996328137:dw

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0the parabola is opening down because the focus is below the directrix

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0But the parabola's focus is at 4, 0. So would that mean the parabola's focus would be shifted to the left 4? Not down 4?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0no, focus has nothing to do with shifting

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Yes, but you put the point at (0, 4) it looks like.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0lel i made a mistake at the drawing suppose to be (0,p)

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Ok, but I'm still confused as to what the standard form would look like?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0the standard form flavor looks like this \[x^2=4py\] or \[y^2=4px\]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0depends on where your parabola opens out

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Ok so since the parabola opens down, would it be y^2 = 4px?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0dw:1438996750393:dw

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0dw:1438996883193:dw

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Oh ok, so it would be in the form of x^2 = 4py?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0So the answer then would be B? @saseal

Loser66
 one year ago
Best ResponseYou've already chosen the best response.0Tip: no need to consider whether p >0 or p <0, if you see the focus, just plug that p in For example, on your problem, focus is (0,4) , hence plug 4 in the form x^2 = 4 p y x^2 = 4*(4) y.

Loser66
 one year ago
Best ResponseYou've already chosen the best response.0then isolate y to get the form.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0should be x^2 = 16y

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0That's not the answer. I just checked.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I think it's y = 1/16x^2

Loser66
 one year ago
Best ResponseYou've already chosen the best response.0surely not \(x^2 = 16y\) divided both sides by 16, you get y = (1/16)x^2

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Ok I was correct. Thank you!

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I wish I could give you all medals.

Loser66
 one year ago
Best ResponseYou've already chosen the best response.0give it to saseal, I have more than 3 thousands of it. hehehe.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Could you guys just check a couple for me? I'm really confused on these, and have them done, just want to make sure they're correct.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Find the vertex, focus, directrix, and focal width of the parabola. x = 3^y2 Would the answer be: Vertex: (0,0) Focus: (1/12,0) Focus Width: .333 or 1/12 Directrix: 1/12

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0\[x=3y^2\]\[y^2=\frac{ 1 }{ 3 }x\]\[y^2 = 4(\frac{ 1 }{ 12 }) x\]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Ok...? So I'm incorrect?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0focus width is wrong and directrix usually they write it as directrix = x = 1/12 so people know which axis it is on

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Oh ok sorry. But my choice for the vertex, focus, and directrix to all remain the same, the focal width has to be .33

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0focal width aka latus rectum = 4p

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0That's not one of my choices. I think they wanted you to solve for the width.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0dw:1438997923182:dw

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0For: A building has an entry the shape of a parabolic arch 74 ft high and 28 ft wide at the base as shown below. Would my answer be: y = −37/98x^2

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0dw:1438998052704:dw

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0so its definitely p<0

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0So what would that mean for the ending answer?

Loser66
 one year ago
Best ResponseYou've already chosen the best response.0To this kind of problem, you need derive from the standard form Vertex (0,74), Two points are (14,0) and (14,0) ok?

Loser66
 one year ago
Best ResponseYou've already chosen the best response.0Vertex form is \(y = a(xh)^2 +k\) \(y = ax^2 + 74\)

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0dw:1438998433802:dw

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0always better t o draw it out haha

Loser66
 one year ago
Best ResponseYou've already chosen the best response.0Now, pick one of the point, I pick (14,0) , that is x =14 , y =0 and plug them in \(0= a (14)^2 +74\) \(a(14)^2 = 74\) \(a = \dfrac{74}{196}\)

Loser66
 one year ago
Best ResponseYou've already chosen the best response.0Now, replace back \(y = \dfrac{74}{196}x^2\) @saseal they didn't say the base of the parabola is the line passed through focus. You cannot apply the form of focus, directrix here.

Loser66
 one year ago
Best ResponseYou've already chosen the best response.0@jdoherty Got what I meant?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Ok, so my answer would be correct then. I do understand. (:

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0yea ikr thats why i didnt use anything to do with focus

Loser66
 one year ago
Best ResponseYou've already chosen the best response.0your answer is (37/98)x^2, that is not correct.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0But I just simplified the fraction, dividing both the top and bottom by 2... And I just have one more question. Find the standard form of the equation of the parabola with a vertex at the origin and a focus at (0, 7). Those still are the most confusing to me.

Loser66
 one year ago
Best ResponseYou've already chosen the best response.0When they give you the focus or directrix, they want you to define the form of the parabola. You know that the focus is ALWAYS inside of the parabola, right? hence ,your parabola is up or down?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0So it would be: y = 1/28 x^2?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0@jdoherty refer to the drawings above to see where the parabola opens up

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I did refer to that, but based on the equation, I got my answer of y = 1/28x^2
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