A homogeneous system has a non-trivial solution $\iff$ the determinant of its coefficient matrix is $0$.
Coefficient matrix $A=\begin{bmatrix}4 & k & 2\\ k & 4 & 1\\ 2 & 2 & 1\end{bmatrix}$. Hence,
$$
\det(A)=
\begin{vmatrix}
4 & k & 2\\
k & 4 & 1\\
2 & 2 & 1
\end{vmatrix}
=-(k-4)(k-2).
$$
Setting $\det(A)=0 \Rightarrow -(k-4)(k-2)=0 \Rightarrow k=2 \text{ or } k=4.$
Therefore, the number of values of $k$ is $\boxed{2}$.
🎓 NIMCET📅 Year: 2020📚 Mathematics🏷 Determinants
3
Let A = (aij) and B = (bij) be two square matricesof order n and det(A) denotes the determinant of A.
Then, which of the following is not correct.