The shell command
"/l/www/moodle/filter/tex/mimetex.linux" -e "/m/floppy/avle/moodledata/filter/tex/d7966e88a6202a803d5c5f564fea438f.gif" -- '\Large \frac{\mathrm d}{\mathrm dx}\frac{1}{n+1} x^{n+1} = \frac{n+1}{n+1} \cdot x^n = x^n.'
returned status = 126
Image not found!
Please try the debugging script