Series Solutions to a 2nd Order Diff. Eq.

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SUMMARY

The discussion focuses on solving the second-order differential equation y'' + y' + xy = 0 using series solutions. Participants emphasize the importance of verifying derived solutions by substituting them back into the differential equation and comparing terms. A critical error identified was the omission of the factor of x in the xy term, which affects the recursion relations. Correcting this mistake is essential for obtaining accurate results in the series expansion.

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  • Understanding of second-order differential equations
  • Familiarity with series solutions and power series expansions
  • Knowledge of recursion relations in differential equations
  • Ability to verify solutions by substitution into differential equations
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  • Study the method of Frobenius for solving differential equations
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  • Explore the derivation of recursion relations in series solutions
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Destroxia
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Homework Statement



y'' + y' + xy = 0

Just want to make sure I understand this completely, I had a bit of trouble towards the end, and thought the -29/600 was a little weird of a fraction to be right. I wasn't given a correct answer to base mine off, so I'm not sure if I'm doing this all right.

Homework Equations


The Attempt at a Solution



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First off, you should always be able to verify that the solution you've derived is actually a solution by plugging it back into the DE and comparing terms order by order. Second, and more directly relevant, in your 5th line, you have lost the factor of ##x## in the 3rd, ##xy## term. Correcting this will significantly change the recursion relations.
 
I think you forgot to increase the exponent of x in the last summation of line 5 when you multiplied through by x.
Already answered above. How come I can't delete this?
 
fzero said:
First off, you should always be able to verify that the solution you've derived is actually a solution by plugging it back into the DE and comparing terms order by order. Second, and more directly relevant, in your 5th line, you have lost the factor of ##x## in the 3rd, ##xy## term. Correcting this will significantly change the recursion relations.

FactChecker said:
I think you forgot to increase the exponent of x in the last summation of line 5 when you multiplied through by x.
Already answered above. How come I can't delete this?

Thank you both, I will rework it and post my answer here.
 

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