If $X_{4 \times 3}, Y_{4 \times 3}$ and $P_{2 \times 3}$ are the matrices, then the order of the matrix $\left[P\left(X^T Y\right)^{-1} P^T\right]^T$ is

If $A=\left[\begin{array}{ll}1 & 2 \\ 3 & 5\end{array}\right]$ and $\alpha, \beta \in R$ are such that $\alpha A^2-\beta A=2 I$, then $\alpha^2+\beta=$

If $\left|\begin{array}{ccc}(1+\alpha)^2 & (1+2 \alpha)^2 & (1+3 \alpha)^2 \\ (2+\alpha)^2 & (2+2 \alpha)^2 & (2+3 \alpha)^2 \\ (3+\alpha)^2 & (3+2 \alpha)^2 & (3+3 \alpha)^2\end{array}\right|=k$ and $\alpha=-2$, then $k=$

7. If the system of equations $x+y+z=5, x+2 y+2 z=6$ and $x+3 y+\lambda z=\mu(\lambda, \mu \in R)$ is solvable by Matrix Inversion Method, then