For which values of kkk is the matrix A=(k2−1k−3)A = \begin{pmatrix} k & 2 \\ -1 & k-3 \end{pmatrix}A=(k−12k−3) singular (non-invertible)?
k=1k = 1k=1 only
k=2k = 2k=2 only
k=1k = 1k=1 and k=2k = 2k=2
No values of kkk make AAA singular