Reference Topics 16-4

This is an interactive site discussing matrix operations:
http://www.mathportal.org/calculators/matrices-calculators/matrix-operations-calculator.php

This is an interactive site finding inverse matrices:
http://www.mathportal.org/calculators/matrices-calculators/matrix-calculator.php

This is a nice matrix operation site which also includes Gauss-Jordan elimination:
http://matrix.reshish.com/inverse.phpSee the whole entry