Is the back of the book wrong? Solving a Differential Equation with Cosh(x)

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SUMMARY

The discussion centers around solving the differential equation y'' - y = cosh(x). The user, Sparky_, questions the accuracy of the answer provided in the back of a textbook, specifically regarding a term with a coefficient of 1/8 on e^x. Another participant clarifies that this term is part of the solution to the homogeneous equation y'' - y = 0 and can be incorporated into the general solution as c1*exp(x) + c2*exp(-x).

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Sparky_
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Homework Statement



Solve : y'' -y = cosh(x)


Homework Equations





The Attempt at a Solution



the attempt is attached.

The answer in the back of the book agree with part of mine. However, the circled part - the part with 1/8 as a coefficient on e^x terms. It's circled on the bottom.

Either the back of the book is wrong (and I'm correct) or this term should cancel and I've missed something.
Help?

Thanks
-Sparky_
 

Attachments

Physics news on Phys.org
The circled term is a solution to the homogeneous equation y''-y=0. It can be absorbed into the c1*exp(x)+c2*exp(-x).
 

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