Find adjoint of each of the matrices : $\left[\begin{array}{ll}1 & 2 \\ 3 & 4\end{array}\right]$

If $\left| {\begin{array}{*{20}{c}}
1&1&1\\
a&b&c\\
{{a^2}}&{{b^2}}&{{c^2}}
\end{array}} \right| = 5$ , then $\left| {\begin{array}{*{20}{c}}
{b{c^2} – {b^2}c}&{{a^2}c – a{c^2}}&{a{b^2} – b{a^2}}\\
{{b^2} – {c^2}}&{{c^2} – {a^2}}&{{a^2} – {b^2}}\\
{c – b}&{a – c}&{b – a}
\end{array}} \right|$ is equal to

Find minors and cofactors of the elements $a_{11}, a_{21}$ in the determinant

$\Delta=\left|\begin{array}{lll}
a_{11} & a_{12} & a_{13} \\
a_{21} & a_{22} & a_{23} \\
a_{31} & a_{32} & a_{33}
\end{array}\right|$

If $a_i^2 + b_i^2 + c_i^2 = 1,\,\,(i = 1,2,3)$ and ${a_i}{a_j} + {b_i}{b_j} + {c_i}{c_j} = 0$ $(i \ne j,i,j = 1,2,3)$ then the value of ${\left| {\,\begin{array}{*{20}{c}}{{a_1}}&{{a_2}}&{{a_3}}\\{{b_1}}&{{b_2}}&{{b_3}}\\{{c_1}}&{{c_2}}&{{c_3}}\end{array}\,} \right|^2}$ is

If $\Delta = \left| {\,\begin{array}{*{20}{c}}{{a_1}}&{{b_1}}&{{c_1}}\\{{a_2}}&{{b_2}}&{{c_2}}\\{{a_3}}&{{b_3}}&{{c_3}}\end{array}\,} \right|$ and ${A_1},{B_1},{C_1}$denote the co-factors of ${a_1},{b_1},{c_1}$ respectively, then the value of the determinant $\left| {\begin{array}{*{20}{c}}{{A_1}}&{{B_1}}&{{C_1}}\\{{A_2}}&{{B_2}}&{{C_2}}\\{{A_3}}&{{B_3}}&{{C_3}}\end{array}} \right|$ is