Settings > Site administration > Plugins > Filters > Manage Filters
Enable Algebra notation and TeX notation
Settings > Site administration > Plugins > Filters > TeX Notation
Check you have a tick next to three required binary paths (latex, dvips, convert)
To install these binaries on SLES:

For Latex: zypper install textlive-latex
For Covert: zypper install ImageMagik

More info http://docs.moodle.org/22/en/TeX_notation_filter