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## Homework Statement

Determine the y_particular solution

## Homework Equations

## The Attempt at a Solution

I've tried this for hours but still don't get the correct value.

This is what I get:

The question is the same as the one I found from http://www4.ncsu.edu/eos/users/s/slc/www/COURSES/File2.pdf (Example 6.11.2).

The correct solution is as follows.

I get the coefficient for e^t is 1/8 and 1/16, but it says that the correct one is 1/4 and 0.

I really have no idea where I got wrong, please help me

[UPDATE]

It turns out that the method of parameter variation REALLY yields DIFFERENT PARTICULAR SOLUTION from method of undetermined coefficients,

Undetermined Coefficient: http://www4.ncsu.edu/eos/users/s/slc/www/COURSES/File2.pdf (Example 6.11.2)

Variation of Parameters: http://www.wolframalpha.com/input/?i=solve+x'+=+-x+++4y+++e^t,+y'+=+x-y+1

So which one is wrong, the undetermined coefficient or variation of parameter for this problem??

Or is it possible that those all are correct answers?

Please help. I'm so confused.

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