For $\lambda \in \mathbb{R}$, calculate the determinant of the matrix $A_\lambda \in \mathcal{M}_d(\mathbb{R})$ having only 1's off the diagonal and only $\lambda$ on the diagonal.
For $\lambda \in \mathbb{R}$, calculate the determinant of the matrix $A_\lambda \in \mathcal{M}_d(\mathbb{R})$ having only 1's off the diagonal and only $\lambda$ on the diagonal.