Variation of parameters - i have different particular soluti

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The discussion revolves around using the variation of parameters method to find a particular solution for a third-order ODE. The user initially encountered different results when rearranging the functions y1, y2, and y3 in the particular solution. Upon further examination, they discovered an error involving an extra factor in their calculations, which led to the discrepancies. The user acknowledged the mistake and emphasized the importance of verifying solutions rather than relying solely on senior guidance. Ultimately, the conversation highlights the significance of careful review in mathematical problem-solving.
omar yahia
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i was trying to get a particular solution of a 3rd order ODE using the variation of parameters method
the homogeneous solution is yh = c1 e-x + c2 ex + c3 e2x
the particular solution is yp=y1u1+y2u2+y3u3
as u1=∫ (w1 g(x) /w) dx , u2=∫ (w2 g(x) /w) dx , u3=∫ (w3 g(x) /w) dx
w =
|y1 y2 y3|
|y'1 y'2 y'3|
|y''1 y''2 y''3|

when i choose y1 , y2 , y3 to be e-x,ex,e2x i get an answer ,
but when i change the arrangement (like: ex,e-x,e2x )
i get another different answer !

so , i have two questions
1 is it normal to have different results when changing who is y1 , y2 , y3 , or am i doing something wrong?
2 if it is normal , does that mean i can have too many different particular solutions , just by changing who is y1 , y2 , y3?
 
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What are the different answers you get?
Maybe they are equivalent, and just look differently?
 
mfb said:
What are the different answers you get?
Maybe they are equivalent, and just look differently?
:smile:
ummmmmm ... ahhhh .. actually ... when you asked me to show the results i went to prepare them for uploading
and as i was rewriting the solution i discovered an extra (2) multiplied in one little tiny term , will i fixed it and went on , and the results were the same indeed , i am terribly sorry for this mistake it happened because i trusted the solution of a senior without a thorough revision
thank you for your reply :smile: and i apologies again.
 
Never trust a senior!
 

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