2. Identity What number is the multiplication identity for real numbers? For matrices, n x n--square matrices, has 1’s on main diagonal and zeros elsewhere 2 x 2 3 x 3

3. Inverse When multiply 2 matrices, A & B, in both orders, you get the identity matrix AB = I BA = I 2 x 2

4. EXAMPLES Find the inverse of the given matrices 1) 2)

5. Solving Matrix Equations Find the inverse of the matrix that is being multiplied by X Multiply both sides of the equation by that inverse Make sure to always write the inverse matrix 1 st (on left side)

6. EXAMPLES Solve the matrix equation 1) 2)

7. Inverses of 3 x 3 Use a graphing calculator Enter Matrix Choose matrix Use key and press enter HW: p227-228 #14-36 even, 37-39