Matrices And Determinants

Let \(\mathrm{A}=\left[\mathrm{a}_{\mathrm{ij}}\right]_{2 \times 2}\), where \(\mathrm{a}_{\mathrm{ij}} \neq 0\) for all \(\mathrm{i}, \mathrm{j}\) and \(\mathrm{A}^{2}=\mathrm{I}\). Let a be the sum of all diagonal elements of \(\mathrm{A}\) and \(\mathrm{b}=|\mathrm{A}|\). Then \(3 a^{2}+4 b^{2}\) is equal to :