Finding the vertex of a parabola from an equation

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    Parabola Vertex
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Discussion Overview

The discussion revolves around finding the vertex of the parabola defined by the equation y² - x + 4y + k = 0, given that it passes through the point (12,1). Participants explore various methods to approach the problem, including differentiation, completing the square, and identifying the type of parabola.

Discussion Character

  • Exploratory, Technical explanation, Homework-related, Mathematical reasoning

Main Points Raised

  • Some participants suggest plugging in the point (12,1) to solve for the constant k.
  • Others question whether the parabola is sideways or vertical, noting that since y is squared, it may be a sideways parabola.
  • There are discussions about rewriting the equation in the form x = f(y) to facilitate finding the vertex.
  • Some participants propose completing the square to express the equation in a standard form that reveals the vertex.
  • One participant mentions that the vertex can be found using the transformation to the form f(y) = x = (y+a)² + b, where the vertex is at (-a, b).

Areas of Agreement / Disagreement

Participants generally agree on the need to find k and the vertex, but there are multiple approaches suggested, and no consensus on a single method or solution has been reached.

Contextual Notes

There are unresolved steps regarding the calculation of k and the transformation of the equation, as well as the implications of the parabola's orientation.

DLxX
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I need help with the following question.

The parabola y^2 - x + 4y + k = 0 passes through the point (12,1). Find the vertex of the parabola.
 
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DLxX said:
I need help with the following question.

The parabola y^2 - x + 4y + k = 0 passes through the point (12,1). Find the vertex of the parabola.


by differentiating ? or the line of symmetry between the roots of the equation ?



or completin the square ?
 
Last edited:
Plug in the point values to solve for k.

What kind of parabola is this? Sideways or vertical? (hint)
 
Jameson said:
Plug in the point values to solve for k.

What kind of parabola is this? Sideways or vertical? (hint)
would be a sideways since the y is squared, but how would i find the h in (h,k)?
 
Show me the equation in the form of x =. Start from there. Did you solve for k?
 
Jameson said:
Show me the equation in the form of x =. Start from there. Did you solve for k?
x = y^2 + 4y + k. So to solve for k do I then plug in 12 and 1 for x and y?
 
DeathKnight said:
Yup that's what you have to do.
Alright so that would give me the k value, but what about the h value?
 
DLxX said:
I need help with the following question.

The parabola y^2 - x + 4y + k = 0 passes through the point (12,1). Find the vertex of the parabola.
plug in values , then just complete the square to put it in the form

f(y) = x = (y+a)^2+b

and b,-a is the vertex
 

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