Pandoc math behaviour
If one uses pandoc to generate \LaTeX{} code from markdown it behaves strange when using mathmode and spaces before closing dollar sign.
$x_1+1=2$ written as $x_1+1=2$ works, but it does not if you have an additional space $x_1+1=2 $.
Then it tries to render it like $x_1+1=2 $ and \TeX{} may fail because of missing/unmatched dollars and math formula outside of math mode.
Minimal working example
Use this markdown file named pandoc.md as input for pandoc and generate a \TeX{} file from it with the following line:
pandoc -t latex -f markdown -o pandoc.tex pandoc.md
Afterwards compile the \LaTeX{} file pandoc_main.tex which contents
\documentclass{article}
\usepackage{hyperref}
\begin{document}
\include{pandoc}
\end{document}
and compile it with e. g.
pdflatex pandoc_main.tex
Feature
This behaviour is desicribed in the man-page for pandoc in the paragraph Extension: tex_math_dollars.
There it says that the opening dollar must be following a space and the closing dollar must not be following a space and must not been followed by a digit.
This prevents one from writing in math mode if one wants to write about economy, lets say about $1,000,000.
Unfortunately \( \) do not work, though pandoc the produced \LaTeX{} code will use this newer style.
So ( x_1+1=2 ) does not render as expected.