Variation of Parameters on a system of Differential Eqs (Simple question)

In summary, the conversation discusses how to solve a system of differential equations using Variation of Parameters. The speaker is asking if their understanding of the complementary solution and fundamental matrix is correct, specifically in the case of repeated roots. They provide an example of the complementary solution and ask for confirmation on the corresponding fundamental matrix. They also mention that the answer to this question will determine if they are in trouble or not.
  • #1
Saladsamurai
3,020
7

Homework Statement


Okay so when solving a system of D.E.s using Variation of Parameters I know that first I find the complementary solution Xc and then do a bunch a of crap after that using the fundamental matrix.

Now I just came across a problem with repeated roots, so I just want to clarify that I am correct in saying that if the complementary solution looks like this:

[tex]X_c=c_1\left(\begin{array}{c}1\\1\end{array}\right)+c_2[\left(\begin{array}{c}1\\1\end{array}\right)t+\left(\begin{array}{c}1\\0\end{array}\right)][/tex]Then the fundamental matrix looks like this:

[tex]\Phi(t)=\left(\begin{array}{cc}1 & t+1\\ 1 & t\end{array}\right)[/tex]
Just a yes or no will do... (if it's no, I am in trouble!)

Thanks!
 
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  • #2
Anyone? I just want to make sure before I go using this...
 
  • #3
Well I thought it was a simple question...
 
  • #4
Tina... eat the food!
 
  • #5
eat the food!
 
  • #6
Saladsamurai said:

Homework Statement


Okay so when solving a system of D.E.s using Variation of Parameters I know that first I find the complementary solution Xc and then do a bunch a of crap after that using the fundamental matrix.

Now I just came across a problem with repeated roots, so I just want to clarify that I am correct in saying that if the complementary solution looks like this:

[tex]X_c=c_1\left(\begin{array}{c}1\\1\end{array}\right)+c_2[\left(\begin{array}{c}1\\1\end{array}\right)t+\left(\begin{array}{c}1\\0\end{array}\right)][/tex]


Then the fundamental matrix looks like this:

[tex]\Phi(t)=\left(\begin{array}{cc}1 & t+1\\ 1 & t\end{array}\right)[/tex]



Just a yes or no will do... (if it's no, I am in trouble!)

Thanks!

Does it help you to point out that

[tex]\left(\begin{array}{cc}1 & t+1\\ 1 & t\end{array}\right)\left(\begin{array}{c}c_1 \\ c_2\end{array}\right)= \left(\begin{array}{c}c_1+ c_2(t+1) \\ c_1+ c_2t\end{array}\right)[/tex]
 

1. What is the variation of parameters method?

The variation of parameters method is a technique used to solve a system of differential equations. It involves finding a particular solution by assuming the form of the solution and then solving for the parameters that make it satisfy the given equations.

2. When is the variation of parameters method used?

This method is typically used when the coefficients of the differential equations are non-constant and cannot be solved using other methods such as separation of variables or the method of undetermined coefficients.

3. How does the variation of parameters method differ from other methods of solving differential equations?

The variation of parameters method involves finding a particular solution by considering a solution in the form of a linear combination of known solutions, whereas other methods such as separation of variables and the method of undetermined coefficients involve finding a general solution.

4. What are the advantages of using the variation of parameters method?

One advantage of using this method is that it allows for the solution of a system of differential equations with non-constant coefficients. It also provides a more general solution compared to other methods which only find particular solutions.

5. Are there any limitations to the variation of parameters method?

One limitation is that it can be more complex and time-consuming compared to other methods. It also may not work for all types of differential equations, and in some cases, it may be difficult to find the particular solution using this method.

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