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TS EAMCET · Maths · Matrices

\(A=\left[\begin{array}{lll}1 & 2 & 2 \\ 2 & 1 & 2 \\ 2 & 2 & 1\end{array}\right]\) then \(A^3-4 A^2-6 A\) is equal to :

  1. A 0
  2. B \(A\)
  3. C \(-A\)
  4. D I
Verified Solution

Answer & Solution

Correct Answer

(C) \(-A\)

Step-by-step Solution

Detailed explanation

\(\because \quad A=\left[\begin{array}{lll}1 & 2 & 2 \\ 2 & 1 & 2 \\ 2 & 2 & 1\end{array}\right]\) \(\therefore \quad A^2=\left[\begin{array}{lll}1 & 2 & 2 \\ 2 & 1 & 2 \\ 2 & 2 & 1\end{array}\right]\left[\begin{array}{lll}1 & 2 & 2 \\ 2 & 1 & 2 \\ 2 & 2 & 1\end{array}\right]\)…