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TS EAMCET · Maths · Matrices

Let \(\mathrm{A}\) be a matrix such that \(\mathrm{AB}\) is a scalar matrix where \(B=\left[\begin{array}{ll}1 & 2 \\ 0 & 3\end{array}\right]\) and \(\operatorname{det}(3 A)=27\). Then \(3 A^{-1}+A^2=\)

  1. A \(\left[\begin{array}{cc}4 & -6 \\ 0 & 2\end{array}\right]\)
  2. B \(\left[\begin{array}{cc}9 & -4 \\ 0 & 3\end{array}\right]\)
  3. C \(\left[\begin{array}{cc}10 & -6 \\ 0 & 2\end{array}\right]\)
  4. D \(\left[\begin{array}{cc}10 & -6 \\ 0 & 4\end{array}\right]\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\left[\begin{array}{cc}10 & -6 \\ 0 & 4\end{array}\right]\)

Step-by-step Solution

Detailed explanation

\begin{aligned} & A=\left[\begin{array}{ll}a & b \\ c & d\end{array}\right] \\ & A B=\left[\begin{array}{ll}a & b \\ c & d\end{array}\right]\left[\begin{array}{ll}1 & 2 \\ 0 & 3\end{array}\right]=\left[\begin{array}{ll}a & 2 a+3 b \\ c & 2 c+3…