Power series method of solving ODE

In summary, the conversation is about finding a recurrence formula using the power series method for the equation y" + y' + sin^2(x)y - 2sinx = 0. One person suggests using the MacLaurin expression for sinx and another person suggests plugging in the expression for sin^2(x) and expanding the series again. The original person is unsure about using the MacLaurin series for sin^2(x) and another person clarifies that it is easier to write a MacLaurin series for cos(2x) instead.
  • #1
femi
4
0
Please can somebody help me with this problem

y" + y' + sin^2(x)y - 2sinx = 0

I used power series method and i used the macclurin expresion for sinx but i was not able to get a recurrence formula.
 
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  • #2
I did not check it but did you try plugging in

[itex]\sin^2(x) = \frac{1-\cos(2x)}{2}[/itex]

and expand your series again?
 
  • #3
Very nice suggestion.
 
  • #4
I cann't get it that way. I think i need to use the macclurin series so that sin^2 will be in terms of x. Pls any other suggestion?
 
  • #5
I have no idea what you mean by "i need to use the macclurin series so that sin^2 will be in terms of x". Of course [itex]sin^2 x[/itex] is in terms of x- that has nothing to do with a series! And trambolin did not mean that you shouldn't use MacLaurin series but that it is far easier to write a MacLaurin series for cos(2x) than to have a MacLaurin series, for sin(x) squared!
 

FAQ: Power series method of solving ODE

What is the power series method of solving ODE?

The power series method of solving ODE (ordinary differential equations) is a technique used to find the solution of a differential equation in the form of a power series. This method is useful when the equation cannot be solved analytically using traditional methods.

How does the power series method work?

The power series method involves expressing the unknown function as a sum of infinite terms, each with increasing powers of the independent variable. The coefficients of these terms are determined by substituting the power series into the differential equation and equating the coefficients of each power of the independent variable to zero.

What types of ODEs can be solved using the power series method?

The power series method can be used to solve linear and some nonlinear ODEs with power series coefficients. It is particularly useful for solving ODEs with singular points, such as those that arise in physics and engineering problems.

What are the advantages of using the power series method?

The power series method provides a systematic approach to solving ODEs and can handle a wide range of problems. It also allows for an infinite number of terms to be included in the power series, providing a more accurate solution as more terms are added.

What are the limitations of the power series method?

The power series method can only be applied to certain types of ODEs with power series coefficients. It also requires a lot of computational power as more terms are added to the series. In some cases, the series may not converge, resulting in an infinite solution. Additionally, the method may not be suitable for real-world problems with complex boundary conditions.

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