Differential Equation Method OF UNDETERMINED COEFF

Click For Summary
SUMMARY

The discussion centers on solving the differential equation y'' - 2y' - 3y = -3te^(-t) using the Method of Undetermined Coefficients. The user initially guessed a solution of y = (At + B)e^(-t) but found it ineffective. Another suggestion was to verify the complementary solution, particularly for y = Ae^(-t), as the accuracy of the book's answer was questioned. The importance of checking the derived solutions by substituting them back into the differential equation was emphasized.

PREREQUISITES
  • Understanding of differential equations, specifically second-order linear equations.
  • Familiarity with the Method of Undetermined Coefficients.
  • Knowledge of complementary solutions for differential equations.
  • Ability to differentiate and verify solutions within the context of differential equations.
NEXT STEPS
  • Review the Method of Undetermined Coefficients in detail.
  • Practice solving second-order linear differential equations with non-homogeneous terms.
  • Learn how to derive and verify complementary solutions for differential equations.
  • Explore common pitfalls in guessing solutions for differential equations.
USEFUL FOR

Students studying differential equations, educators teaching advanced mathematics, and anyone seeking to master the Method of Undetermined Coefficients in solving differential equations.

FahimP
Messages
12
Reaction score
0

Homework Statement


I have been trying to solve this differential equation by Method of Undetermined Coefficients for a long time.

y"-2y'-3y=-3te^(-t) ......

We are supposed to guess a solution then differentiate and go from there. I guessed
y = (At + B)e^(-t) .... but this does not work. ... can someone help me on this ... I have also tried y = Ae^(-t) but this also doesn't work. Is it possible the book answer is wrong ?


Homework Equations





The Attempt at a Solution

 
Physics news on Phys.org
You first need to solve the homogeneous equation. What solution do you get to that?
 
FahimP said:

Homework Statement


I have been trying to solve this differential equation by Method of Undetermined Coefficients for a long time.

y"-2y'-3y=-3te^(-t) ......

We are supposed to guess a solution then differentiate and go from there. I guessed
y = (At + B)e^(-t) .... but this does not work. ... can someone help me on this ... I have also tried y = Ae^(-t) but this also doesn't work. Is it possible the book answer is wrong ?

Of course it's possible the book is wrong. It is also possible that you are wrong. You shouldn't have to "guess" what to try if you have the complementary solution.

I suggest you re-check your work for Ae-t. And if you get an answer you can always check it for yourself by plugging it into the DE.
 

Similar threads

  • · Replies 7 ·
Replies
7
Views
2K
Replies
10
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 15 ·
Replies
15
Views
3K
Replies
7
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
Replies
7
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K