Solution of an ODE in series Frobenius method

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SUMMARY

The forum discussion focuses on solving the ordinary differential equation (ODE) represented by the equation $$xy'' + y' + xy = 0$$ using the Frobenius method. The user is struggling to reverse a series expansion given by $$J(x) = 1 - \frac{1}{x^2} + \frac{3x^4}{32} - \frac{5x^6}{576}...$$ and its reciprocal. The general formula for the series is provided as $$\sum_{n=0}^{\infty} \frac{(-1)^n}{(n!)^2}(\frac{x}{2})^2$$. The discussion highlights the challenges of manipulating series in the context of differential equations.

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  • Understanding of ordinary differential equations (ODEs)
  • Familiarity with the Frobenius method for series solutions
  • Knowledge of series expansions and their manipulations
  • Basic calculus, particularly derivatives and series convergence
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  • Study the Frobenius method in detail, focusing on its application to ODEs
  • Learn about series manipulation techniques, specifically reversing series
  • Explore the properties of power series and their convergence
  • Investigate the application of generating functions in solving differential equations
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Mathematicians, physics students, and anyone interested in solving ordinary differential equations using series methods, particularly those studying advanced calculus or differential equations.

Caglar Yildiz
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Hi
I am supposed to find solution of $$xy''+y'+xy=0$$
but i am left with reversing this equation.
i am studying solution of a differential equation by series now and I cannot reverse a series in the form of:
$$ J(x)=1-\frac{1}{x^2} +\frac{3x^4}{32} - \frac{5x^6}{576} ...$$

$$ \frac{1}{J}=1+\frac{x^2}{2} +\frac{5x^4}{32}+ \frac{23x^6}{576}...$$

General formula of $J(x)$ is $$\sum_{n=0}^{\infty} \frac{(-1)n}{(n!)^2}(\frac{x}{2})^2$$

Thanks for all help!
 
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