If \( A = \dfrac{1}{5! \; 6! \; 7!} \)
, then \( \left| \operatorname{adj}(\operatorname{adj}(2A)) \right| \) is equal to:
Let \( \alpha \) and \( \beta \) be real numbers. Consider a \( 3 \times 3 \) matrix \( A \) such that \( A^{2}=3A+\alpha I \). If \( A^{4}=21A+\beta I \), then:
