$$c = \sqrt{a^2 + b^2}$$$$c = \sqrt{a^2 + b^2}$$

This is an inline equation $c = \sqrt{a^2 + b^2}$.

$$F(k) = \int_{-\infty}^{\infty} f(x) e^{2\pi i k} dx$$$$ \lvert x \rvert$$