Variation of Parameters problem

Click For Summary
SUMMARY

The forum discussion centers on solving the differential equation t²y'' - 2y = 3t² - 1 using the method of variation of parameters. The user presents their solution as Y(t) = t²ln(t) - (1/3)t² + (1/2), while the reference book states Y(t) = t²ln(t) + (1/2). The discrepancy arises from an error in the user's integration process, specifically in the second integral, which leads to the incorrect inclusion of the -1/3t² term. The discussion emphasizes the importance of showing work to identify mistakes in mathematical solutions.

PREREQUISITES
  • Understanding of second-order differential equations
  • Familiarity with the method of variation of parameters
  • Proficiency in integration techniques
  • Ability to analyze and compare mathematical solutions
NEXT STEPS
  • Review the method of variation of parameters in differential equations
  • Practice integration techniques, focusing on definite and indefinite integrals
  • Study error analysis in mathematical problem-solving
  • Explore LaTeX for formatting mathematical expressions effectively
USEFUL FOR

Students studying differential equations, mathematics educators, and anyone seeking to improve their problem-solving skills in calculus and integration techniques.

pergradus
Messages
137
Reaction score
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 Y(t) = t^2ln(t) - \frac{1}{3}t^2 + \frac{1}{2}

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

I don't understand why they are off by the 1 term?
 
Physics news on Phys.org
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.
 
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.
 

Attachments

  • CIMG0015.jpg
    CIMG0015.jpg
    16.4 KB · Views: 563

Similar threads

  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 13 ·
Replies
13
Views
1K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 11 ·
Replies
11
Views
2K