Class CBSE Class 12 Mathematics Matrices and Determinants Q #729
KNOWLEDGE BASED
APPLY
1 Marks 2024 MCQ SINGLE
If A is a square matrix of order 3 such that the value of \(|adj\cdot A|=8,\) then the value of \(|A^{T}|\) is: (1)
(A) \(\sqrt{2}\)
(B) \(-\sqrt{2}\)
(C) 8
(D) \(2\sqrt{2}\)

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Step-by-Step Solution

Given that A is a square matrix of order 3 and \(|adj \cdot A| = 8\).

We know that \(adj(A) = |A|A^{-1}\), so \(|adj(A)| = |A|^{n-1}\) where n is the order of the matrix.

Also, \(|adj \cdot A| = |adj(A)| \cdot |A|\)

Since A is of order 3, \(|adj(A)| = |A|^{3-1} = |A|^2\)

Therefore, \(|adj \cdot A| = |A|^2 \cdot |A| = |A|^3\)

Given \(|adj \cdot A| = 8\), so \(|A|^3 = 8\)

Taking the cube root of both sides, we get \(|A| = \sqrt[3]{8} = 2\)

We need to find the value of \(|A^T|\). We know that the determinant of a transpose of a matrix is equal to the determinant of the original matrix, i.e., \(|A^T| = |A|\)

Therefore, \(|A^T| = 2\)

Correct Answer: 2

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Pedagogical Audit
Bloom's Analysis: This is an APPLY question because it requires students to apply the properties of adjoint and determinant of a matrix to find the value of the determinant of the transpose of the matrix.
Knowledge Dimension: PROCEDURAL
Justification: The question requires the student to follow a procedure involving the properties of determinants and adjoints to arrive at the solution.
Syllabus Audit: In the context of CBSE Class 12, this is classified as KNOWLEDGE. The question directly tests the student's knowledge of matrix properties and determinant calculations as covered in the textbook.