If $A = \begin{bmatrix} 2 & -1 \\ -7 & 4 \end{bmatrix}$ and $B = \begin{bmatrix} 4 & 1 \\ 7 & 2 \end{bmatrix}$,then which of the following is correct?

Which of the following matrices is not a square matrix?

If $A$ and $B$ are symmetric matrices of the same order,then which one of the following is not true?

Find $AB,$ if $A=\left[\begin{array}{ll}6 & 9 \\ 2 & 3\end{array}\right]$ and $B=\left[\begin{array}{lll}2 & 6 & 0 \\ 7 & 9 & 8\end{array}\right].$

If $A = \begin{bmatrix} 1 & 2 \\ 3 & 5 \end{bmatrix}$ and $\alpha, \beta \in \mathbb{R}$ are such that $\alpha A^2 - \beta A = 2I$, then $\alpha^2 + \beta =$

If $P = \begin{bmatrix} 1 & 2 & 3 \\ 2 & 3 & 4 \\ 3 & 4 & 5 \end{bmatrix} \begin{bmatrix} -1 & -2 \\ -2 & 0 \\ 0 & -4 \end{bmatrix} \begin{bmatrix} -4 & -5 & -6 \\ 0 & 0 & 1 \end{bmatrix}$,then $P_{22} = $