1.

If \(\begin{bmatrix} 1 & -3 & 2 \\\ 2 & -8 & 5 \\\ 4 & 2 & λ \end{bmatrix}\) is not an invertible matrix, then what is the value of λ ?1. -12. 03. 14. 2

Answer» Correct Answer - Option 3 : 1

Concept:

If the matrix A is not an invertible matrix then | A | = 0

If the matrix A is the non-singular matrix then | A |  0 

 

Calculations:

Given, A = \(\begin{bmatrix} 1 & -3 & 2 \\\ 2 & -8 & 5 \\\ 4 & 2 & λ \end{bmatrix}\)is not an invertible matrix

As we know, If the matrix A is non invertible matrix then | A | = 0

⇒ \(\begin{vmatrix} 1 & -3 & 2 \\\ 2 & -8 & 5 \\\ 4 & 2 & λ \end{vmatrix}\) = 0

⇒ 1\(\rm (-8\lambda - 10)+3(2\lambda-20)+2(4+32)\) = 0

⇒ \(\rm -8\lambda - 10+6\lambda-60+72 = 0\)

\(\rm -2\lambda +2 = 0\)

\(\rm \lambda = 1\)

Hence, If \(\begin{bmatrix} 1 & -3 & 2 \\\ 2 & -8 & 5 \\\ 4 & 2 & λ \end{bmatrix}\) is not an invertible matrix, then the value of λ is 1.



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