How Do You Solve (2x-y+1)dx+(x+y)dy=0 Using a Linear Transformation?

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Discussion Overview

The discussion revolves around solving the differential equation (2x-y+1)dx+(x+y)dy=0 using a linear transformation. Participants explore various methods for transforming the equation, including finding intersections of lines and translating axes to simplify the equation into a homogeneous form.

Discussion Character

  • Technical explanation
  • Exploratory
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants suggest making a linear transformation to simplify the equation, though there is uncertainty about how to perform this transformation.
  • One participant proposes finding the intersection of the lines y=2x+1 and y=-x as part of the transformation process.
  • Another participant argues that the objective is to remove constant terms to obtain a homogeneous equation, suggesting a translation of axes.
  • There is a discussion about the difference between linear and affine transformations, with some participants clarifying that an affine transformation includes constant terms.
  • One participant describes a method involving a change of variables to eliminate certain terms in the equation, aiming to simplify it for standard solution methods.
  • Another participant mentions converting the equation to polar coordinates as a potential method for analysis.
  • Some participants express frustration with the complexity of the equation and the difficulty in extracting meaningful data from it.
  • A participant shares their verification of the solution using Mathematica, expressing confidence in the correctness of their approach, while also seeking more efficient plotting methods.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the best method for solving the equation. Multiple competing views and approaches are presented, with ongoing debate about the effectiveness of different transformations and methods.

Contextual Notes

There are unresolved mathematical steps and dependencies on definitions related to transformations. The discussion reflects various assumptions about the nature of the transformations and their implications for solving the differential equation.

  • #31
Yes, you're right~
There's lots of different approaches to a question~
It's just that...
You guys are amazing!
I'd never of thought to come up with those ideas~
It makes me want to start jumping into mathematics books and brush up on my math~
 
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  • #32
After homogenizing, the generic solution to the polar form looks like the product of these four terms to various powers: (if I haven't made a mistake)

(A + B tan θ + C tan² θ)
exp(arctan(D tan θ + E))
sec θ
exp(θ)

times some constant.

Sigh, not all that enlightening. :frown: Everything except the "some constant" depend on the coefficients in the original problem.
 

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