Review, as much as necessary, how to do matrix addition, multiplication of a matrix by a scalar, matrix multiplication, determinant of a matrix (\(2\times 2\) and \(3\times 3\)), and inverse of a matrix (\(2\times 2\) only). You might find the information at the following links useful.
There is nothing to turn in, but you will soon be given a brief in-class quiz (see the course schedule for the date) that asks you to multiply two \(3\times 3\) matrices and also asks you to calculate the determinant of a \(3\times 3\) matrix (by hand).