Finding regular singular point

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SUMMARY

The differential equation \(x^2y'' + \sin(x)y' - y = 0\) has a regular singular point at \(x=0\). This conclusion is drawn from the criteria that both \(p(x) = \frac{\sin(x)}{x}\) and \(q(x) = -\frac{1}{x^2}\) are not analytic at \(x=0\), while \((x-0)p(x)\) and \((x-0)^2q(x)\) are analytic at this point. The indicial equation can be determined by analyzing the series expansion of \(\sin(x)\) around \(x=0\).

PREREQUISITES
  • Understanding of differential equations, specifically the form \(y'' + p(x)y' + q(x)y = 0\)
  • Knowledge of analytic functions and singular points
  • Familiarity with Taylor series expansions
  • Ability to manipulate power series
NEXT STEPS
  • Study the properties of regular singular points in differential equations
  • Learn how to derive the indicial equation from a differential equation
  • Explore the Taylor series expansion of \(\sin(x)\) and its implications
  • Investigate the analytic behavior of functions around singular points
USEFUL FOR

Students and researchers in mathematics, particularly those focusing on differential equations and singularity analysis, will benefit from this discussion.

BearY
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Homework Statement


Show that ##x^2y''+sin(x)y'-y = 0## has a regular singular point at ##x=0##, determine the indicial equation and it's roots.

Homework Equations


For a DE in the form of ##y''+p(x)y'+q(x)y=0##, if both ##p(x)## and ##q(x)## are not analytic at ##x=x_0##, and both ##(x-x_0)p(x)## and ## (x-x_0)^2q(x)## are analytic at ##x=x_0##,
##x_0## is a singular regular point of the DE.

The Attempt at a Solution


I can't justify why ##\frac{sin(x)}{x}## is analytic at 0. Basically stucked at first step, so I am afraid no attempt worth mentioning.

Nevermind, I just realized that ##\frac{sin(x)}{x}## can be written as power series expension.
 
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BearY said:

Homework Statement


Show that ##x^2y''+sin(x)y'-y = 0## has a regular singular point at ##x=0##, determine the indicial equation and it's roots.

Homework Equations


For a DE in the form of ##y''+p(x)y'+q(x)y=0##, if both ##p(x)## and ##q(x)## are not analytic at ##x=x_0##, and both ##(x-x_0)p(x)## and ## (x-x_0)^2q(x)## are analytic at ##x=x_0##,
##x_0## is a singular regular point of the DE.

The Attempt at a Solution


I can't justify why ##\frac{sin(x)}{x}## is analytic at 0. Basically stucked at first step, so I am afraid no attempt worth mentioning.

Look at the Taylor series of ##\sin(x)##. Divide it by ##x##.
 
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