Solving Separable ODEs: How to Integrate with Functions of t?

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Discussion Overview

The discussion revolves around the integration of separable ordinary differential equations (ODEs), specifically focusing on the integration of functions of time. Participants explore the integration process for equations of the form di(t)/dt = i(t)p(t) and express confusion regarding the integration of terms involving functions of t.

Discussion Character

  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant expresses understanding of basic integration but struggles with integrating di(t)/dt = i(t)p(t) and questions how to perform the integral on the left side, noting the presence of di(t) instead of dt.
  • Another participant confirms their ability to integrate ∫(du/u) but seeks clarification on the terminology for integrating ∫di(t)/i(t).
  • There is a discussion about the equivalence of ∫(du/u) and ∫(du(t)/u(t)), with emphasis on the notation indicating that u is a function of t.

Areas of Agreement / Disagreement

Participants generally agree on the equivalence of the integrals discussed, but there remains uncertainty regarding the integration process and terminology for functions of time.

Contextual Notes

Participants have not resolved the confusion regarding the integration of di(t)/i(t) and the appropriate terminology to use in this context.

dgamma3
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I understand how to integrate this: ∫y2dy.

I don't understand how to integrate this:
di(t)/dt = i(t)p(t)
intergrate((di(t)/dt/i(t))*dt = p(t)dt) (see this image: http://i.imgur.com/OdKI309.png)

how do you perform the intergral on the left, seeing as as it not dt, but di(t)?

thanks
 
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dgamma3 said:
I understand how to integrate this: ∫y2dy.

I don't understand how to integrate this:
di(t)/dt = i(t)p(t)
intergrate((di(t)/dt/i(t))*dt = p(t)dt) (see this image: http://i.imgur.com/OdKI309.png)

how do you perform the intergral on the left, seeing as as it not dt, but di(t)?

thanks
Can you do this integration? ##\int \frac{du}{u}?##

BTW, there are no such words in English as "intergrate" and "intergral."
 
Mark44 said:
Can you do this integration? ##\int \frac{du}{u}?##

BTW, there are no such words in English as "intergrate" and "intergral."

Yes I can do that.

But I do not understand how do integrate (what word do I use?)
∫di(t)/i(t)
 
Last edited:
dgamma3 said:
Yes I can do that.

But I do not understand how do integrate (what word do I use?)
∫di(t)/i(t)
This is essentially the same as what I wrote.
##\int \frac{du}{u}## is the same as ##\int \frac{du(t)}{u(t)}##. The only difference is that in the second integral, it is made explicit that u is a function of t.
 
Mark44 said:
This is essentially the same as what I wrote.
##\int \frac{du}{u}## is the same as ##\int \frac{du(t)}{u(t)}##. The only difference is that in the second integral, it is made explicit that u is a function of t.
Thank you Mark!
 

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