For inline math, enclose it in `\\(...\\)`.

For displayed formulas, use `\[...\]`.

These render differently.

Inline-mode looks like
\\( \sum_{i=0}^n i^2 = \frac{(n^2+n)(2n+1)}{6} \\) that.


Display-mode looks like
\[\sum_{i=0}^n i^2 = \frac{(n^2+n)(2n+1)}{6}\]
that.