How do I solve this Nonlinear First Order Differential Equation?

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Discussion Overview

The discussion revolves around a nonlinear first-order differential equation presented by a participant who is self-studying differential equations. The equation involves the output function h(t) and an input function q(t). Participants explore methods for linearization and finding a transfer function.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Exploratory

Main Points Raised

  • One participant confirms that the equation is a nonlinear first-order differential equation but struggles with linearization using Taylor Series.
  • Another participant attempts to manipulate the equation using calculus, suggesting a form of linearization but does not provide a definitive method.
  • A later post reiterates the original problem, adding a potential simplification of the equation.
  • Some participants suggest integrating the equation as a possible first step, although no further details are provided on this approach.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the linearization process and the best approach to take. There is no consensus on how to proceed with solving the equation or finding the transfer function.

Contextual Notes

Participants have not resolved the mathematical steps necessary for linearization or integration, and there are dependencies on the definitions of the functions involved.

pvgomes07
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Hello!

I am taking a self study diff e course, and I have run into a problem with no one to ask for help.
Here is the problem:

d/dt [ h^3(t) + 3h(t)^2 + 3h(t) ] = q(t)

h(t) is output.
q(t) is input.

is this Nonlinear First Order Differential Equation.
But I could not expand to Taylor Series for linearization... :/

I'm trying to find the transfer function.

Thanks!
 
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It should be basic Calculus that
\frac{d}{dx}(h^3+ 3h^2+ 3h)= q(t)
3h^2\frac{dh}{dt}+ 6h\frac{dh}{dt}+ 3\frac{dh}{dt}= (3h^2+ 6h+ 3)\frac{dh}{dt}= q(t)
Now what is the linearization of that?
 
pvgomes07 said:
Hello!

I am taking a self study diff e course, and I have run into a problem with no one to ask for help.
Here is the problem:

d/dt [ h^3(t) + 3h(t)^2 + 3h(t) ] = q(t)

h(t) is output.
q(t) is input.

is this Nonlinear First Order Differential Equation.
But I could not expand to Taylor Series for linearization... :/

I'm trying to find the transfer function.

Thanks!

Maybe this will help:

h3 + 3 h2 + 3h = (h +1)3 -1
 
Hi !
Why not imtegrate it first ?
 

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JJacquelin said:
Hi !
Why not imtegrate it first ?

Yeah! Thank you very much!
:)
 

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