Defining a macro for showing math formula source

Question

I would like to typeset an introduction to MathJAX/LaTeX formulae.

For that, I introduced a macro:

\newcommand{\showsource}[1]{$#1$ : \verb|#1|}

To typeset a math formula and then show its source.

But when I use it as

\showsource{\frac{1}{2}}

XeLaTeX complains about a missing $.

How can I write such a macro correctly?

Edit (MWE -- Manuel Kuehner)

\documentclass{article}

\newcommand{\showsourceA}[1]{$#1$}
\newcommand{\showsourceB}[1]{verb|#1|}

\begin{document}
\showsourceA{\frac{1}{2}}
\showsourceB{\frac{1}{2}}
\end{document}

Answer 1

Followin Steven B. Segletes' comment and his link:

Print small TeX code verbatim and render it

I created a new, working macro:

\newcommand{\showsource}[1]{$#1$ \quad {\ttfamily\detokenize{#1}} }

and it works on

\showsource{\frac{1}{2}}

(yes, the space after \frac is strange but I can live with it).