Rantonels has a wordpress trick (used here) to display LaTeX formula as an image: see his wp blog post and Wordpress LaTeX support Thus javascript is not needed for mathjax.js to work. But is it legit if page is not hosted on wordpress?
\ddot \vec r = - \frac{GM_2}{r^2} + \frac{\Lambda c^2}{3} r


MathJax tutorial and quick reference
See: MathJax Getting Started: When \(a \ne 0\), there are two solutions to \(ax^2 + bx + c = 0\) and they are \(x = {-b \pm \sqrt{b^2-4ac} \over 2a}.\)

You can test this online using jsbin.com but it renders fine locally in file mode (without local web server)

$$\left [ - \frac{\hbar^2}{2 m} \frac{\partial^2}{\partial x^2} + V \right ] \Psi = i \hbar \frac{\partial}{\partial t} \Psi$$

$$f(a) = \frac{1}{2\pi i} \oint\frac{f(z)}{z-a}dz$$

$$\vec{\nabla} \times \vec{F} = \left( \frac{\partial F_z}{\partial y} - \frac{\partial F_y}{\partial z} \right) \mathbf{i} + \left( \frac{\partial F_x}{\partial z} - \frac{\partial F_z}{\partial x} \right) \mathbf{j} + \left( \frac{\partial F_y}{\partial x} - \frac{\partial F_x}{\partial y} \right) \mathbf{k}$$

$$\sigma = \sqrt{ \frac{1}{N} \sum_{i=1}^N (x_i -\mu)^2}$$

$$\hbar \frac{\partial}{\partial t} \Psi = \hat H\Psi$$

$$ \lim_{x \to +\infty} \frac{3x^2 +7x^3}{x^2 +5x^4} = 3 $$

These examples use inline LaTeX.
\(\ddot a\) : \ddot a to put a double dot over a, and \(\vec a\) to put a little arrow over a.
\(\bar a\) : \bar a to put an overbar over a | \(\tilde a\) : \tilde a to put '~' over a
\(\hat a\) : \hat a to put '^' over a | \(\dot a\) : \dot a to put a single dot over a

PhysicsForums Reference   \(\Lambda^\mu_\nu,\ \Lambda_\nu^\mu,\ \Lambda^\mu{}_\nu,\ \Lambda_\nu{}^\mu\) and \(\lim_{n\rightarrow +\infty} {\frac{\sin(x)}{x}}\)

MathJax tutorials, tips, references, etc

Wikipedia MathJax| MathJax docs| Github MathJax| jsfiddle MathJax.Hub.Config example|
MathJax uses CSS with web fonts or SVG, instead of bitmap images or Flash, so equations scale with surrounding text at all zoom levels.

LaTeX tutorials, tips, references, etc

Wikipedia LaTeX| Very nice LaTeX reference| Astrobites: Getting Stared with LaTeX|
Overleaf.com| Overleaf intro to LaTeX tutorial|
PhysicsForums How to type math equations here and short (very nice) intro to LaTeX
/r/LaTeX| LaTeX Project links|
Short tutorial| LaTeX reference card| LaTeX symbol list| Long tutorial| Long tutorial_2|
LaTeX wikibook | wiki math | LaTeX templates|
List of document markup languages| Mathematics: Writing & Research Tools| MathML|

Online LaTeX equation editors

LaTex Base| SciWeavers| HostMath| CodeCogs| FormulaSheet| TutorialsPoint| RCortesi| LaTeX4Technics|