MathJax is an open source JavaScript display engine for mathematics that works in all modern browsers.
When \(a \ne 0\), there are two solutions to \(ax^2 + bx + c = 0\) and they are $$x = {-b \pm \sqrt{b^2-4ac} \over 2a}.$$
\( \cos(\theta) + \sin(\theta) = 2 / \pi \).