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CUET · MATHS · PYQ PAPER 2023

If \(A=\left[\begin{array}{cc}2 & 3 \\ -1 & 1\end{array}\right]\) and \(A^2-3 A+k I=0\), then the value of \(k\) is:

  1. A -5
  2. B 3
  3. C 5
  4. D -3
Verified Solution

Answer & Solution

Correct Answer

(C) 5

Step-by-step Solution

Detailed explanation

\( Tr(A) = 2+1 = 3 \) \( \det(A) = (2)(1) - (3)(-1) = 2+3 = 5 \) \( A^2 - Tr(A)A + \det(A)I = 0 \) \( A^2 - 3A + 5I = 0 \) \( k=5 \)
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