Undetermined coefficient method

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SUMMARY

The forum discussion centers on solving the differential equation y'' + 10y' + 25y = x + 2 + 3e^{-5x} using the undetermined coefficient method. The user confirms that the complementary solution, yc = C1*e^{-5x} + C2*xe^{-5x}, is correct. However, the initial guess for the particular solution, yp = ax + b + C*e^{-5x}, is incorrect. The correct form for the particular solution is yp = ax + b + C*x^2*e^{-5x}, as the terms e^{-5x} and xe^{-5x} already satisfy the homogeneous equation, necessitating the inclusion of x^2.

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Homework Statement


y''+10y'+25y=x+2+3e-5*x

Homework Equations

The Attempt at a Solution


F(D) = D2+10D+25 zeroes: -5
yc= C1*e-5*x + C2*e-5*x *x

yp = ax+b + C*e-5*x
yp = ax+b + C*e-5*x*x2

I just want to know if my yc and yp is correct, after that I know how to do it.
 
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yc is correct, yp is not. The SECOND yp, ax+ b+ cx^2e^{-5x} is correct. Since e^{-5x} and xe^{-5x} satisfy the associated homogenous equation you need the "x^2".
 

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