remove broken math example

[jekyll-link-tag]: https://jekyllrb.com/docs/liquid/tags/#link

## Adding Formatted Equations

The template supports rendering of equations via [KaTeX](https://katex.org/).

This option must be activated by adding `math: true` to the `_config.yml` file 

or YAML front matter of the Markdown file where you wish to use it.

Mathematical expressions can then be added to the page content using the LaTeX syntax.

Expressions can be written inline:

~~~

{% raw %}Inline expressions can be added between `$` symbols, e.g. $E = Mc^2$.{% endraw %}

~~~

{: .source}

with the result:

Inline expressions can be added between `$` symbols, e.g. $E = mc^2$.

Or as a block across multiple lines:

~~~

{% raw %}$$

    \lim_{x \rightarrow 0}

    \frac{

        \sin x

    } {

        x

    }

    = 1

$${% endraw %}

~~~

{: .source}

with the result:

$$

    \lim_{x \rightarrow 0}

    \frac{

        \sin x

    } {

        x

    }

    = 1

$$

The example above was taken from the chapter _Typesetting Mathematical Formulae_,

in [The Not So Short Introduction to LaTeX](https://tobi.oetiker.ch/lshort/lshort.pdf).

[The Mathematics chapter of the LaTeX WikiBook](https://en.wikibooks.org/wiki/LaTeX/Mathematics)

is a good reference guide for those wishing to add equations

and mathematical expressions to their lessons.

{% include links.md %}