Khan Academy: Linear Algebra: Formula for 2 X 2 Inverse

A video lesson in which a formula is derived for finding the inverse of a 2 x 2 matrix. Addresses that a 2 x 2 matrix is only invertible if the determinant is not equal to 0. Defines the determinant and shows two examples of calculating the determinant and using it to find the inverse of a matrix when possible. [18:20]