The shell command
"/l/www/moodle/filter/tex/mimetex.linux" -e "/m/floppy/avle/moodledata/filter/tex/809f39b10132df134e65e64ba340fa2f.gif" -- '\Large \displaystyle \frac{dy}{dx} = \frac{x}{y} '
returned status = 126
Image not found!
Please try the debugging script