Sketching Ellipses: Comparing 0 and 8

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Discussion Overview

The discussion revolves around sketching the equations of two curves, specifically 0 = x² - 2x + 4y² and 8 = x² - 2x + 4y². Participants are exploring how to determine if these equations represent ellipses and the methods for sketching them.

Discussion Character

  • Exploratory
  • Mathematical reasoning

Main Points Raised

  • Some participants inquire about the best methods for sketching the given equations and how to confirm they are both ellipses.
  • One participant suggests completing the square in x as a potential approach to analyze the equations.
  • Another participant asks for clarification on the general equation for an ellipse in Cartesian coordinates and the relevance of completing the square.
  • A participant presents a transformation of the equation, showing how (x - 1)² + y² relates to the original equation.

Areas of Agreement / Disagreement

Participants are generally exploring the same problem but have not reached a consensus on the methods or the implications of their findings regarding the equations.

Contextual Notes

There are unresolved steps in the mathematical reasoning, particularly regarding the completion of the square and its application to the equations in question.

JC3187
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Hi guys,

What is the best way to sketch

0 = x2 - 2x + 4y2 And
8 = x2 - 2x + 4y2

?

How do I sketch these two and how do I know they're both ellipses?
Thank you.
 
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JC3187 said:
Hi guys,

What is the best way to sketch

0 = x2 - 2x + 4y2 And
8 = x2 - 2x + 4y2

?

How do I sketch these two and how do I know they're both ellipses?
Thank you.

Complete the square in [itex]x[/itex]: [itex]x^2 - 2ax = (x - a)^2 - a^2[/itex].
 
Then what do i do?
 
JC3187 said:
Then what do i do?
What is the general equation for an ellipse in Cartesian coordinates? Can you see why completing the square helps?
 
[tex](x- 1)^2+ y^2= x^2- 2x+ 1+ y^2[/tex]
Do you see how that is connected to [tex]x^2+ 2x+ y^2[/tex]?
 

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