Let A=[a_i j]_2 × 2, where a_i j ≠ 0 for all i, j and A^2=I. Let a be the sum of all diagonal elements of A and b=|A|. Then 3 a^2+4 b^2 is equal to

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