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AP EAMCET · Maths · Matrices

The sum of the values of \(x\) so that the matrix \(\left(\begin{array}{lll}2 & 2 & 1 \\ 1 & 3 & 1 \\ 1 & 2 & 2\end{array}\right)-x\left(\begin{array}{lll}1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 1\end{array}\right)\) is singular, is

  1. A 3
  2. B 5
  3. C 7
  4. D 9
Verified Solution

Answer & Solution

Correct Answer

(C) 7

Step-by-step Solution

Detailed explanation

Let a matrix \[ =\left[\begin{array}{lll} 2 & 2 & 1 \\ 1 & 3 & 1 \\ 1 & 2 & 2 \end{array}\right]-x\left[\begin{array}{lll} 1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 1 \end{array}\right]=\left[\begin{array}{ccc} 2-x & 2 & 1 \\ 1 & 3-x & 1 \\ 1 & 2 & 2-x \end{array}\right] \] \(\because\)…