Differential Equations Variation of Params Problems

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SUMMARY

The discussion centers on solving the differential equation t² * y'' - 2y = 3t² - 1 using the Variation of Parameters method. The participants analyze the Wronskian determinant, calculated as W = -3, and attempt to find the particular solution Y. The user initially arrives at an incorrect solution, Y = 3/10*t⁴ - t² * ln|t|/3, while the correct answer is Y = t² * ln|t| + 1/2. The discrepancy arises from an error in setting up the integrals for the Variation of Parameters method.

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  • Understanding of second-order differential equations
  • Familiarity with the Variation of Parameters method
  • Knowledge of Wronskian determinants
  • Basic integration techniques
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  • Practice calculating Wronskian determinants for various functions
  • Study common mistakes in solving differential equations
  • Explore alternative methods for solving non-homogeneous differential equations
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Students and educators in mathematics, particularly those focusing on differential equations, as well as anyone seeking to improve their problem-solving skills in this area.

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Homework Statement



[tex]t^{2}[/tex] * y'' - 2y = [tex]3t^{2}[/tex] - 1

[tex]y_{1}[/tex] = t[tex]^{2}[/tex]

[tex]y_{2}[/tex] = 1/t

Homework Equations



Variation of Params formula
wronskian det

The Attempt at a Solution



W = t^2 * -t^-2 -[1/t * 2t] = -3

Y = -t^2 * Integral[ (-1/3)(1/t)(3t^2 -1)] + 1/t * Integral[(-1/3)(t^2)(3t^2 -1)]

I get an answer that is not correct so I guess I set this part up wrong somehow anyone see the error?

My answer: Y = 3/10*t^4 - t^2 * ln|t|/3

Correct Answer: Y = t^2*ln|t| + 1/2
 
Last edited:
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So I figured I ended up getting the correct answer but going the long way and solving the system using

u*t^2 + v * 1/t = 3t^2 -1

but I still have no idea why the integral gave me the wrong answer apparently I missed something somewhere, if you feel like going through please let me know what I messed up on.
 

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