Inverse Matrices

The inverse of matrix A, written A^-1, is the matrix that satisfies AA^-1 = I. A matrix only has an inverse if its determinant is not zero. For a 2 × 2 matrix ⎡a  b⎣⎡c  d⎣ with determinant 1, the inverse is ⎡d  -b⎣⎡-c  a⎣.