For what value of is the matrix singular?

MATHEMATICS · Subjective · AP · AP Precalculus · Functions with Parameters, Vectors, and Matrices · Functions with Parameters, Vectors, and Matrices

Problem

For what value of

k

is the matrix

C=\begin{pmatrix}1 & 2 & 3\\ 4 & k & 6\\ 7 & 8 & 9\end{pmatrix}

singular?