General Solution of the first order differential equation

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Discussion Overview

The discussion centers on finding the general solution of the first-order differential equation given by dy/dt + y = Σ Sin(nt)/n². Participants explore methods for solving this equation, including the use of integrating factors and integration techniques.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant presents the equation dy/dt + y = Σ Sin(nt)/n² and suggests a method involving multiplying by an integrating factor.
  • Another participant proposes using an integrating factor of the form exp(1)dt, leading to a simplification of the left-hand side to d(y.exp(t))/dt.
  • There is a question regarding whether Σ represents a constant or an infinite sum, with a clarification that it is indeed an infinite sum.
  • A later reply corrects the integrating factor suggestion, indicating it should be exp(t) instead of exp(1).

Areas of Agreement / Disagreement

Participants express differing views on the form of the integrating factor and the interpretation of Σ, indicating that multiple competing views remain and the discussion is not resolved.

Contextual Notes

There are unresolved assumptions regarding the nature of Σ and the specific form of the integrating factor, which may affect the proposed solutions.

Yr11Kid
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dy/dt + y = Sigma Sin(nt)/n^2
 
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Multiply by exp(-(integral)Sigma Sin(nt)/n^2 dx) ) and integrate.
 
I think that this is a linear equation that requires an integrating factor of the form: exp(1)dt. Multiply both side of the equation by this factor. The LHS reduce to d(y.exp(t))/dt. You can then integrate both side.
 
Is Sigma simply a constant of do you mean an infinite sum?
\frac{dy}{dt}+ y= \sum_{n=1}^\infty \frac{sin(nt)}{n^2}

In any case henlus' suggestion works- although he meant "integrating factor of the form exp(t)", not exp(1).
 
Last edited by a moderator:
HallsofIvy said:
Is Sigma simply a constant of do you mean an infinite sum?
\frac{dy}{dt}+ y= \sum_{n=1}^\infty \frac{sin(nt)}{n^2}

In any case henlus' suggestion works- although he meant "integrating factor of the fore exp(t)", not exp(1).

You're right.
 

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