### The Cauchy-Schwarz Inequality (TeX)

$\left( \sum_{k=1}^n a_k b_k \right)^2 \leq \left( \sum_{k=1}^n a_k^2 \right) \left( \sum_{k=1}^n b_k^2 \right)$

### Standard Deviation (MathML)

$σ=1N∑i=1N(xi−μ)2.$

### Inline equation (TeX)

Finally, while display equations look good for a page of samples, the ability to mix math and text in a paragraph is also important. This expression $$\sqrt{3x-1}+(1+x)^2$$ is an example of an inline equation. As you see, MathJax equations can be used this way as well, without unduly disturbing the spacing between lines.