Can someone help me i don't understand this DE

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Homework Help Overview

The discussion revolves around a differential equation of the form xy'' - 4y' = x^4, focusing on finding the general solution, which includes both the homogeneous and particular solutions.

Discussion Character

  • Mathematical reasoning, Problem interpretation, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to solve the differential equation and compares their results with those from a textbook and WolframAlpha. They express confusion regarding the presence of a term in their particular solution that seems to be omitted in the referenced solutions.

Discussion Status

Participants are exploring the validity of the original poster's solution and discussing the conventions regarding the inclusion of terms from the homogeneous solution in the particular solution. Some guidance has been offered regarding the combination of like terms.

Contextual Notes

There is an implied assumption that the solutions should adhere to standard practices in solving differential equations, particularly regarding the treatment of homogeneous and particular solutions.

iScience
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problem: xy''-4y'=x^4

when i solve it i get y(homogeneous)=C1+C2x^5 which is fine because that's what the back of the book says

but for the particular solution, i get .. C1=-(1/25)x^5 , C2=(1/5)lnx

so y(general)= C1+C2x^5-(1/25)x^5+(1/5)lnx(x^5)

but wolframalpha as well as the back of my book both say the answer is...
y(general)=C1+C2x^5+(1/5)lnx(x^5)

where does the -(1/25)x^5 term go?...
 
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You have
C1 x5 + C2 x5 = C3x5

Does that help?
 
Last edited:
so technically my answer is correct and they just combined the x^5 terms.. i see
 
Thanks!
 
If you're finding the general solution of an ODE, then usually you would not allow pieces of the homogeneous solution to show up in the particular solution.
 

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