MCQ
If the matrix $\begin{bmatrix}1 &\text{amp;3}& \text{amp}\lambda+2 \\2& \text{amp;4}&\text{amp;8} \\3&\text{amp;5}&\text{amp;}10 \end{bmatrix}$ is singular, then $\lambda=$
  • A
    -2
  • B
    4
  • 2
  • D
    -4

Answer

Correct option: C.
2
A matrix is singular if and only if it has a determinant of 0.
$\begin{bmatrix}1 &\text{amp;3}& \text{amp}\lambda+2 \\2& \text{amp;4}&\text{amp;8} \\3&\text{amp;5}&\text{amp;}10 \end{bmatrix}$

$(40-40)-2(20-24)+(\lambda+2)(10-12)=0$

$2\lambda=4$

$\Rightarrow\lambda=2$

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