Non exact differential equation, initial value problem

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SUMMARY

The discussion centers on solving the non-exact differential equation y''' - 9y' = 54x - 9 - 20e^(2x) with initial conditions y(0) = 8, y'(0) = 5, and y''(0) = 38. The correct solution is identified as y = 2 + 2e^(3x) + 2e^(-3x) - 3x^2 + x + 2e^(2x). The primary error in the attempted solution was the omission of the constant term from the derivative calculation, specifically the constant 1 from the term (x)'.

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Homework Statement


I am trying to solve the following:
y'''-9y'=54x-9-20e^2x with y(0)=8, y'(0)=5, y''(0)=38

Homework Equations

The Attempt at a Solution


upload_2016-12-8_9-34-25.png

upload_2016-12-8_9-34-52.png


The right answer is:
y= 2+2e^3x+2e^(-3x)-3x^2+x+2e^2x

I am only wrong on the coefficients C2 and C3. Where did I mess up in my solution?
 
Physics news on Phys.org
When computing ##y'## at the top of the second you are missing the constant ##1## coming from ##(x)'##=1.
 

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