Solve by using variation of parameters

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SUMMARY

The discussion focuses on solving the non-constant coefficient differential equation x²y''(x) - 3xy'(x) + 3y(x) = 2x⁴e^x using the method of variation of parameters. The participants identify this as an "Euler type" or "equi-potential" equation and suggest the substitution t = ln(x) to transform it into a problem with constant coefficients. This substitution simplifies the equation, allowing for easier application of standard solution techniques.

PREREQUISITES
  • Understanding of differential equations, specifically second-order linear equations.
  • Familiarity with the method of variation of parameters.
  • Knowledge of Euler type equations and their characteristics.
  • Basic calculus, including differentiation and substitution techniques.
NEXT STEPS
  • Study the method of variation of parameters in detail.
  • Learn about Euler type equations and their solutions.
  • Practice transforming differential equations using substitutions like t = ln(x).
  • Explore examples of solving constant coefficient differential equations.
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Mathematics students, educators, and professionals dealing with differential equations, particularly those interested in advanced solution techniques for non-constant coefficient problems.

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x²y"(x)-3xy'(x)+3y(x)=2(x^4)(e^x)

=>y"(x)-(3/x)y'(x)+(3/x²)y(x)=2x²e^x

i don't know how to approach this problem because the coefficients are not constant and i am used to being given y1 and y2

HELP!
 
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This is an "Euler type" or "equi-potential" equation. The substitution t= ln(x) will change it to a "constant coefficients" problem in the variable t.

[tex]\frac{dy}{dx}= \frac{dy}{dt}\frac{dt}{dx}= \frac{1}{x}\frac{dy}{dt}[/tex]
and, differentiating again,
[tex]\frac{d^2y}{dx^2}= \frac{d}{dx}\left(\frac{dy}{dx}\right)[/tex][tex]= \frac{d}{dx}\left(\frac{1}{x}\frac{dy}{dt}\right)= -\frac{1}{x^2}\frac{dy}{dt}+ \frac{1}{x^2}\frac{d^2y}{dt^2}[/tex]
 
HallsofIvy said:
This is an "Euler type" or "equi-potential" equation. The substitution t= ln(x) will change it to a "constant coefficients" problem in the variable t.

[tex]\frac{dy}{dx}= \frac{dy}{dt}\frac{dt}{dx}= \frac{1}{x}\frac{dy}{dt}[/tex]
and, differentiating again,
[tex]\frac{d^2y}{dx^2}= \frac{d}{dx}\left(\frac{dy}{dx}\right)[/tex][tex]= \frac{d}{dx}\left(\frac{1}{x}\frac{dy}{dt}\right)= -\frac{1}{x^2}\frac{dy}{dt}+ \frac{1}{x^2}\frac{d^2y}{dt^2}[/tex]
thank you very much. i appreciate the help
 

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