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TS EAMCET · Maths · Matrices

Let \(I\) be a unit matrix of order 6 . Let \(A=\left(a_{i j}\right)\) be a square matrix of order 6 such that \(a_{i j}=\left\{\begin{array}{l}1, \text { if } i+j=7 \\ 0, \text { if } i+j \neq 7\end{array}\right.\) then \(\left(A(\operatorname{adj} A) A^{-1}\right) A^2=\)

  1. A 1
  2. B \(A\)
  3. C \(-A\)
  4. D -1
Verified Solution

Answer & Solution

Correct Answer

(C) \(-A\)

Step-by-step Solution

Detailed explanation

Given that, \(a_{i j}= \begin{cases}1, & \text { if } i+j=7 \\ 0, & \text { if } i+j \neq 7\end{cases}\) Now, \(\left(A(\operatorname{adj} A) A^{-1}\right) A^2=\left(A(\operatorname{Adj} A) A^{-1}\right) A^2\) \(=\left((|A| I) A^{-1}\right) A^2 \quad[\because A\) adj…