Math not rendering correctly in .html

[vishrutarya]

Hi I've recently installed MMD5 and want to use it in text that includes math. I'm using Fletcher's documentation on math but I'm not generating the same output. Here's what I'm doing:

Input: .txt file

Here’s some math:

$${x}_{1,2}=\frac{-b\pm \sqrt{{b}^{2}-4ac}}{2a}$$ 

end.

Processing: Command-line code

multimarkdown file.txt > file.html

Output: Actual (.html)

Here’s some math:

\[{x}_{1,2}=\frac{-b\pm \sqrt{{b}^{2}-4ac}}{2a}\]

end.

Output: Desired (.html)
The eqn. on fletcher's page.

Additional info.
I installed on a Mac el capitan via the homebrew route on the instructions page.

[fletcher]

The actual output you describe appears correct (check the source of the page you reference to verify).

Did you properly set up the metadata, as described on that same page?

[vishrutarya]

Adding the metadata solved the problem. Thanks, Fletcher. My bad for not realizing the metadata was necessary for the desired output.