## Algebra and Trigonometry 10th Edition

When there is an inverse of a matrix $A A^{-1}$ = I (the Identity Matrix) AB = $\begin{bmatrix} 3(.4) + 2(-.1) & 3(-.2) + 2(.3) \\ 1(.4) +4(-.1) & (1)(-.2) + 4(.3)\\ \end{bmatrix}$ = $\begin{bmatrix} 1 & 0\\ 0 & 1 \end{bmatrix}$ Since AB equals the identity matrix, B is the inverse of A.