For which value of kkk is det(k22k)=0\det \begin{pmatrix} k & 2 \\ 2 & k \end{pmatrix} = 0det(k22k)=0?
k=2k = 2k=2
k=−2k = -2k=−2
k=2k = 2k=2 and k=−2k = -2k=−2
No value of kkk