Author Topic: non-homogeneous guessing question  (Read 728 times)

Weina Zhu

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non-homogeneous guessing question
« on: October 08, 2018, 10:37:22 AM »
during solving the general solution for the non-homogeneous equation, why should we guessing an answer combine sin&cos together for
an equation like the right-hand side only contains one of the sin&cos.

Thanks!

Victor Ivrii

Because derivative of sine is cosine and v.v. Try to solve $y''+y'=\cos(x)$ as with $y=a\cos(x)$.