Finding regular singular point

In summary: The resulting series will converge for ##x=0##, therefore ##\frac{\sin(x)}{x}## is analytic at ##x=0##.In summary, the given differential equation has a regular singular point at ##x=0##. The indicial equation and its roots can be determined using the criteria for a singular regular point. The attempt at a solution involves finding the Taylor series of ##\sin(x)## and dividing it by ##x##, which shows that ##\frac{\sin(x)}{x}## is analytic at ##x=0##.
  • #1
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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  • #2
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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What is a regular singular point?

A regular singular point is a point in the complex plane where the coefficients of a differential equation are analytic and the solution of the equation is also analytic.

How do you find regular singular points?

To find regular singular points, you need to first rewrite the differential equation in its standard form and then examine the behavior of the coefficients near each point in the complex plane. Regular singular points will have analytic coefficients, while irregular singular points will have non-analytic coefficients.

Why is it important to find regular singular points?

Finding regular singular points is important because it allows us to determine the behavior and properties of the solutions to a differential equation. It also helps to identify the type of differential equation and the methods that can be used to solve it.

What are some methods for solving a differential equation with a regular singular point?

Some common methods for solving a differential equation with a regular singular point include the Frobenius method, the power series method, and the Laplace transform method. These methods involve expanding the solution in a series and using analytic techniques to determine the coefficients.

Can a regular singular point have multiple solutions?

Yes, a regular singular point can have multiple solutions. This is because the behavior of the solution near a regular singular point can vary depending on the coefficients of the differential equation. This can result in multiple solutions that satisfy the equation at the same point.

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