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CUET · MATHS · PYQ PAPER 2023

If \(A=\left[\begin{array}{cc}2 & 3 \\ 5 & -2\end{array}\right]\) then:

  1. A \(A^{-1}=\frac{1}{11} A\)
  2. B \(A^{-1}=\frac{1}{19} A\)
  3. C \(A^{-1}=-\frac{1}{19} A\)
  4. D \(A^{-1}=\frac{1}{7} A\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(A^{-1}=\frac{1}{19} A\)

Step-by-step Solution

Detailed explanation

\(|A| = (2)(-2) - (3)(5) = -4 - 15 = -19\) \(A^{-1} = \frac{1}{|A|} \text{adj}(A) = \frac{1}{-19} \left[\begin{array}{cc}-2 & -3 \\ -5 & 2\end{array}\right]\) \(A^{-1} = \frac{1}{19} \left[\begin{array}{cc}2 & 3 \\ 5 & -2\end{array}\right] = \frac{1}{19} A\)