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2 posts tagged with mathematics by PuGZ.

Displaying 1 through 2 of 2.

## Fourier series confusion and pre/post-integration substitution dilemmas.

Asking for a friend: With the use of Fourier series, I'm trying to solve an ODE of the form L*y'' + R*y' + y/C = r(x), where r(x) = 1 - x^2 for |x| <= 1, i.e. has a period of 2. To do so I need to represent 1 - x^2 as a Fourier series. In doing so I have to integrate e^(-n * i * pi * x), but I've reached a stumbling block. [more inside]

## Inequalities and direction-flipping

Why is it that when I solve the inequality 0 ≤ arccos(x) <> cos(π/4)? Why do the operators switch direction? [more inside]

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