3. Consider the generic 2 \times 2 matrix $A = \begin{bmatrix} a & b \\ c & d \end{bmatrix}$. (a) What is $|A|$? (You can use the quick formula) (b) What is $A^{-1}$? (You can use the quick formula) (c) Use $A^{-1}$ to find $|A^{-1}| (d) Verify that $|A^{-1}| = |A|^{-1}$.
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