The quadratic formula: \(ax^2 + bx + c = 0\)

$$x = {-b \pm \sqrt{b^2-4ac} \over 2a}$$

Euler's identity: \(e^{i\pi} + 1 = 0\)

Cauchy's integral: \[f(a) = \frac{1}{2\pi i} \oint\frac{f(z)}{z-a}dz\]