Variation of Parameters problem

In summary, the conversation discusses finding a particular solution using the method of variation of parameters for the equation t2y'' - 2y = 3t2 - 1, given y1 = t2 and y2 = t-1. The conversation also mentions two different solutions, one with a -1/3t2 term and one without, and the possibility of an error in the second integral.
  • #1
pergradus
138
1

Homework Statement



Find a particular solution by method of variation of parameters:

t2y'' - 2y = 3t2 - 1

given:

y1 = t2
y2 = t-1

Homework Equations



img9.gif


The Attempt at a Solution



I get [tex]Y(t) = t^2ln(t) - \frac{1}{3}t^2 + \frac{1}{2}[/tex]

The book gives [tex] Y(t) = t^2ln(t) + \frac{1}{2} [/tex]

I don't understand why they are off by the 1 term?
 
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  • #2
The only thing I can tell you is that they aren't off by one term- you are!

And since you don't show any work, we can't say why you are. I suspect you have an error in your second integral.
 
  • #3
HallsofIvy said:
The only thing I can tell you is that they aren't off by one term- you are!

And since you don't show any work, we can't say why you are. I suspect you have an error in your second integral.

By "they" I was referring to the the two answers - mine and theirs.

And I made no mistakes in the integration - check my work if you want. This is the THIRD time I've done this problem and I get the same answer.

It will take me hours to type this in LaTex so please just look at picture I uploaded. The -1/3t2 term just doesn't go away.
 

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What is the "Variation of Parameters problem"?

The Variation of Parameters problem is a method used to find a particular solution to a non-homogeneous linear differential equation. It is an alternative method to solving these types of equations, instead of using the traditional method of undetermined coefficients.

When is the Variation of Parameters method used?

The Variation of Parameters method is used when solving non-homogeneous linear differential equations with constant coefficients. It is particularly useful when the non-homogeneous term cannot be easily guessed, or when the traditional method of undetermined coefficients fails.

How does the Variation of Parameters method work?

The Variation of Parameters method involves finding a particular solution by using a set of functions that are linearly independent from the general solution of the homogeneous equation. These functions are then substituted into the original equation, and the coefficients are solved for using the method of undetermined coefficients.

What are the advantages of using the Variation of Parameters method?

One advantage of using the Variation of Parameters method is that it can be used for a wider range of non-homogeneous equations compared to the traditional method of undetermined coefficients. It also allows for a more systematic and efficient approach to solving these types of equations.

Are there any limitations to using the Variation of Parameters method?

One limitation of the Variation of Parameters method is that it can be more time-consuming and complex compared to the traditional method of undetermined coefficients. It also requires a good understanding of linear algebra and differential equations in order to accurately solve the equations.

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