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COMEDK · Maths · 21. Matrices

Matrix \(A = \begin{bmatrix} 1 & 1 & 2 \\ 1 & -2 & 2 \\ 1 & 0 & -1 \end{bmatrix}\),
Given \(M_{22}\) and \(A_{32}\) are the minor and cofactor of the adjoint matrix of A respectively then the value of the expression \(M_{22} + A_{32} - |adj\ A|\) is:

  1. A \(-117\)
  2. B \(-729\)
  3. C \(-99\)
  4. D \(-81\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(-81\)

Step-by-step Solution

Detailed explanation

The given matrix is \(A = \begin{bmatrix} 1 & 1 & 2 \\ 1 & -2 & 2 \\ 1 & 0 & -1 \end{bmatrix}\). First, we find the determinant of matrix \(A\): \(|A| = 1((-2)(-1) - (2)(0)) - 1((1)(-1) - (2)(1)) + 2((1)(0) - (-2)(1))\) \(|A| = 1(2) - 1(-3) + 2(2) = 2 + 3 + 4 = 9\) Using the…