# Questions tagged [differential-equations]

Ordinary or partial differential equations. Delay differential equations, neutral equations, integro-differential equations. Well-posedness, asymptotic behavior, and related questions.

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### Math education problem solved [closed]

https://imgur.com/Bzg8Si4 anyone is can solved this problem ? $$y'=\frac{-\sin2x\arctan(\sin x)}{\sin y\cos y}(\sin^4y+\cos^4y)$$
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### Is there a standard definition of weak form of a nonlinear PDE?

Comments on the question Are those distributional solutions that are functions, the same as weak solutions? suggest there might not be a standard definition of the weak form of a non-linear PDE. Is ...
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### Are those distributional solutions that are functions, the same as weak solutions?

There are two closely related concepts and I am not sure exactly how close. Consider a partial differential equation. (The coefficients need not be constant but assume they are functions, and not ...
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### Is square of Delta function defined somewhere?

everyone. I am wondering whether anyone knows if the square of Dirac Delta function is defined somewhere. In the beginning, this question might look strange. But by restricting the space of the test ...