I have this matrix:
$ \begin{pmatrix} a & b \\ c & d \end{pmatrix} $
and I want to show a new user how to type this, by adding \$ \$:
\$ \begin{pmatrix} a & b \\ c & d \end{pmatrix} \$,
which doesn't make what's inside the brackets text.
How do you fix this?
If you want some part of text not to be rendered, simply include it in backticks, like this:
`$ \begin{pmatrix} a & b \\ c & d \end{pmatrix} $`.
You will get: $ \begin{pmatrix} a & b \\ c & d \end{pmatrix} $.
So you could leave a comment like:
To write down a matrix you can use the syntax
$ \begin{pmatrix} a & b \\ c & d \end{pmatrix} $- like here $ \begin{pmatrix} a & b \\ c & d \end{pmatrix} $.
Double dollars are not a way to achieve this - they are used for centered formulas. Writing $$ \begin{pmatrix} a & b \\ c & d \end{pmatrix} $$ gives you this: $$ \begin{pmatrix} a & b \\ c & d \end{pmatrix}$$
And - as you checked yourself - \$ ... \$ does not work in this way either. You probably used this because you are used to this from LaTeX. (Still you can use \$ inside math mode - as in $\$$ which renders as $\$$ - but that's not what you need here.)
