This document discusses inverse matrices. An inverse matrix A-1 undoes the transformation of the original matrix A such that multiplying A by A-1 or A-1 by A results in the identity matrix. The identity matrix is a square matrix with 1s on the main diagonal and 0s elsewhere. It leaves a matrix unchanged when multiplied. The determinant of a square matrix transforms it into a scalar value and is used to calculate the inverse. Sample problems demonstrate calculating the inverse of a 2x2 matrix.