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If A=[21−103−2k10]A = \begin{bmatrix} 2 & 1 & -1 \\ 0 & 3 & -2 \\ k & 1 & 0 \end{bmatrix} is non-singular matrix, then the value(s) of kk belongs to:

[Where RR is the set of real numbers]

Solution

✅ Correct Option: 3

Expanding along the first row:

∣A∣=2(0+2)−1(0+2k)+(−1)(0−3k)=4−2k+3k=4+k|A| = 2(0+2) - 1(0+2k) + (-1)(0-3k) = 4 - 2k + 3k = 4 + k.

A matrix is non-singular when ∣A∣≠0|A| \neq 0, so 4+k≠04 + k \neq 0, i.e. k≠−4k \neq -4.

Hence k∈R−{−4}k \in R - \{-4\}.

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