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If A=[6453]A = \begin{bmatrix} 6 & 4 \\ 5 & 3 \end{bmatrix} and B=adj(A)B = adj(A), then ∣B∣|B| is equal to:

Solution

✅ Correct Option: 2

∣A∣=6⋅3−4⋅5=18−20=−2|A| = 6 \cdot 3 - 4 \cdot 5 = 18 - 20 = -2.

For n×nn \times n matrix, ∣adj A∣=∣A∣n−1|adj\ A| = |A|^{n-1}.

Here n=2n = 2, so ∣B∣=∣adj A∣=∣A∣1=−2|B| = |adj\ A| = |A|^{1} = -2.

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