Solving y=e^{t-t^2/2}: Luck or Methodology?

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Discussion Overview

The discussion revolves around the solution of the equation y=e^{t-t^2/2}, exploring methods to derive this solution and addressing the nature of the equation itself. Participants engage in various substitution techniques and clarify the context of the equation, including its parameters and form.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant expresses uncertainty about the methodology used to arrive at the solution y=e^{t-t^2/2}, suggesting that their approach felt like luck.
  • Another participant proposes substituting y=ekx as a potential method to solve the equation.
  • A different participant attempts a substitution of the form y=e^{k(x)}, leading to a Riccati equation and ultimately arriving at a solution involving integrals.
  • Several participants question the formulation of the equation, pointing out that y'' + ty' + ty is not a complete equation without context, and seek clarification on whether y is a function of t or x.
  • One participant mentions having solved the question but expresses dissatisfaction with their solution and requests resources for deriving error function Laplace transforms.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the methods for solving the equation or the nature of the equation itself. Multiple competing views and uncertainties remain regarding the appropriate substitutions and the formulation of the problem.

Contextual Notes

There are limitations in the discussion regarding the clarity of the equation's parameters and the completeness of the provided information, which may affect the understanding of the problem.

Wxfsa
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I know [itex]y=e^{t-t^2/2}[/itex] is a solution but how do I reach it? I tried substituting y=uv, making u' terms disappear then I noticed that the resulting u''=(__)u could be solved by a gaussian but this seems like luck to me
 
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Have you tried substituting y=ekx?
 
AdityaDev said:
Have you tried substituting y=ekx?
[itex]e^{kx}[/itex] cannot be a solution but I decided to try [itex]e^{k(x)}[/itex] which gave me a ricatti equation and after I substituted [itex]k=q\frac{p'}{p}[/itex] I got the original equation

edit: this is the solution
[itex]c_1e^{\frac{-x^2}{4}+x}+c_2e^{\frac{-x^2}{4}+x} \int ^x e^{\frac{-s^2}{2}+2s}ds[/itex]
 
Last edited:
A little nitpicky, but y'' + ty' + ty is not an equation (differential or otherwise), so it doesn't make any sense to talk about a solution. Is the full equation y'' + ty' + ty = 0?
 
Mark44 said:
A little nitpicky, but y'' + ty' + ty is not an equation (differential or otherwise), so it doesn't make any sense to talk about a solution. Is the full equation y'' + ty' + ty = 0?
yes
 
Mark44 said:
A little nitpicky, but y'' + ty' + ty is not an equation (differential or otherwise), so it doesn't make any sense to talk about a solution. Is the full equation y'' + ty' + ty = 0?
More nitpicking: Is y supposed to be a function of t or a function of x with t as a parameter?
 
Svein said:
More nitpicking: Is y supposed to be a function of t or a function of x with t as a parameter?

you don't have to answer the question if you don't want to
 
I actually solved this qustion after much work, however I do not like m solution. It would be great if someone could link me somewhere that derives error function laplace transforms

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Svein said:
More nitpicking: Is y supposed to be a function of t or a function of x with t as a parameter?

Wxfsa said:
you don't have to answer the question if you don't want to
Of course that's true, but if you're asking for help with a problem, it's best to provide as much information about the problem as you can.
 

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