# Mathjax and image descriptions interact inconsistently between the edit preview and actual post

When trying to edit the image description in this question to

diagram showing an inclined plane at angle $$\α\$$ and an angry bird being fired at angle $$\β\$$ at speed $$\u\$$,

(raw text is diagram showing an inclined plane at angle $α$ and an angry bird being fired at angle $β$ at speed $u$)

the edit preview shows

whereas if I save the edit, the post instead looks like this:

Note the bit of the image description immediately before the first $ is shown next to the image (and that the first bit of Mathjax, $\alpha\\$, is rendered).