Finding general solution of linear ODE inhomogeneous

In summary, the conversation discusses finding the general solution to a differential equation and correcting a mistake in the particular solution. The correct general solution is determined to be y = c1e6x + c2e-4x + 5xe6x + Bsin(x) + Ccos(x). It is also mentioned that the constant A should be equal to 5.
  • #1
ohspyro89
13
0

Homework Statement


Find the general solution to y''-2y'-24y=50e6x-14cos(x)-175sin(x)


Homework Equations


I can't figure out how to solve for B,C,D, and E. I'm wondering if I did something wrong.



The Attempt at a Solution



I'm attaching photos, since it'd take forever to type this all out. I'm stuck on this one, and I'm working on another problem at the same time.

IMAG0209.jpg

IMAG0210.jpg

IMAG0211.jpg
 
Physics news on Phys.org
  • #2
it should be factored as (m-6)(m+4)
not (m-6)(m-4) ill look at the rest.
 
  • #3
Yes, you did something wrong. Your particular solution should be
yp = Axe6x + Bsin(x) + Ccos(x)

The general solution will be y = c1e6x + c2e-4x + yp
 
  • #4
*Face-Palm*

Alright, I'll work on it. Thanks guys!

Also, was I right to get rid of one of the +-i for the undetermined coefficients part? So, now I don't have a D and E to worry about, but it covers the cosx-sinx.
 
  • #5
You really don't need either of the +/- i pairs. If your roots of the char. equation include +/- i, the solutions will include e^(ix) and e^(-ix), but you can take a linear combination of these and work with cos(x) and sin(x) instead.
 
  • #6
How's this? I got a constant to be zero, which seems odd to me. Is this the right general solution?

IMAG0212.jpg
 
  • #7
A should equal 5
 
  • #8
Looks reasonable - you can check it yourself. Is y'' - 2y' - 24y = 50e6x-14cos(x)-175sin(x) an identity? IOW, if you replace the 3 terms on the left with your solution and its first two derivatives, do you end up with what you have on the right?
 

Related to Finding general solution of linear ODE inhomogeneous

1. What is a general solution for a linear ODE with inhomogeneous terms?

A general solution for a linear ODE with inhomogeneous terms is an equation that includes both the complementary function (the solution to the corresponding homogeneous equation) and the particular integral (a specific solution to the inhomogeneous equation). This allows for all possible solutions to the equation to be accounted for.

2. How do you find the complementary function for a linear ODE with inhomogeneous terms?

To find the complementary function for a linear ODE with inhomogeneous terms, you first solve the corresponding homogeneous equation by setting the inhomogeneous terms to zero. This will give you a general solution in terms of arbitrary constants. Then, you can use the method of undetermined coefficients or variation of parameters to find a particular solution for the inhomogeneous terms. The sum of the complementary function and particular integral will give you the general solution.

3. What is the method of undetermined coefficients?

The method of undetermined coefficients is a technique used to find a particular solution for an inhomogeneous linear ODE. It involves assuming a form for the particular solution based on the form of the inhomogeneous terms and then solving for the coefficients using substitution. This method is most effective when the inhomogeneous terms have a simple form, such as polynomials, exponentials, or trigonometric functions.

4. How does variation of parameters work for finding a particular solution?

Variation of parameters is another method for finding a particular solution to an inhomogeneous linear ODE. This method involves finding a set of solutions to the corresponding homogeneous equation and then using them to construct a particular solution in terms of a set of parameters. These parameters are then determined using substitution and boundary conditions. This method is more general than the method of undetermined coefficients and can be used for more complex inhomogeneous terms.

5. Can the general solution for a linear ODE with inhomogeneous terms always be found?

Yes, the general solution for a linear ODE with inhomogeneous terms can always be found using the methods described above. However, the complexity of the inhomogeneous terms and the equation itself may make the solution more difficult to obtain. In some cases, numerical methods may be necessary to approximate the solution.

Similar threads

  • Calculus and Beyond Homework Help
Replies
5
Views
459
  • Calculus and Beyond Homework Help
Replies
3
Views
724
  • Calculus and Beyond Homework Help
Replies
3
Views
696
  • Calculus and Beyond Homework Help
Replies
3
Views
586
  • Calculus and Beyond Homework Help
Replies
1
Views
849
  • Calculus and Beyond Homework Help
Replies
2
Views
682
  • Calculus and Beyond Homework Help
Replies
3
Views
1K
  • Calculus and Beyond Homework Help
Replies
3
Views
914
  • Calculus and Beyond Homework Help
Replies
2
Views
462
Replies
13
Views
2K
Back
Top