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CUET · MATHS · PYQ PAPER 2025

If \(\left[\begin{array}{ll}3 & 1 \\ 2 & 1\end{array}\right] A\left[\begin{array}{ll}2 & 1 \\ 1 & 1\end{array}\right]=\left[\begin{array}{ll}1 & 1 \\ 0 & 1\end{array}\right]\), then matrix ' \(A\) ' is

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

Answer & Solution

Correct Answer

(C) \(\left[\begin{array}{cc}1 & -1 \\ -3 & 4\end{array}\right]\)

Step-by-step Solution

Detailed explanation

\( B^{-1} = \left[ \begin{array}{ll} 3 & 1 \\ 2 & 1 \end{array} \right]^{-1} = \frac{1}{3 \cdot 1 - 1 \cdot 2} \left[ \begin{array}{cc} 1 & -1 \\ -2 & 3 \end{array} \right] = \left[ \begin{array}{cc} 1 & -1 \\ -2 & 3 \end{array} \right] \)…
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