Helpful Links
The above is a matrices calculator which I used frequently during my time in linear algebra for checking my answers when doing practice questions as well as determining specific properties of matrices such as what happens with inverse matrices. you can preform almost any sort of operation as well as edit the demission's of the matrices
Desmos is fairly well known website which you will definitely be using during your time at the Mount particularly for a few of the classes Dr. Daven tends to teach such as Fundamentals of mathematical Reasoning it is also completely free