Given that the matrix $A=\begin{bmatrix} a_{11} &a_{12} \\ a_{21} &a_{22} \end{bmatrix}$ and Eigen value are $1,-2$ and Corresponding Eigen Vectors are $X_{1}=\begin{bmatrix} 1\\2 \end{bmatrix}$ and $X_{2}=\begin{bmatrix} 9\\1 \end{bmatrix}$
Find the $1)\sum a_{ij},$when $i=j$
$2)Det(A)$
$3)$Sum of all Elements in the given matrix