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CUET · MATHS · PYQ PAPER 2023

Given \(X=\left[\begin{array}{cc}1 & 0 \\ -1 & 7\end{array}\right]\), then value of K if \(X^2=8 X+K I\) is :

  1. A \(-7\)
  2. B 7
  3. C 8
  4. D 5
Verified Solution

Answer & Solution

Correct Answer

(A) \(-7\)

Step-by-step Solution

Detailed explanation

\(\det(X - \lambda I) = \det\left(\begin{bmatrix} 1-\lambda & 0 \\ -1 & 7-\lambda \end{bmatrix}\right) = (1-\lambda)(7-\lambda) = \lambda^2 - 8\lambda + 7\) Characteristic equation: \(\lambda^2 - 8\lambda + 7 = 0\) By Cayley-Hamilton theorem:…