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TS EAMCET · Maths · Matrices

If \(M\) and \(N\) are square matrices of order 3 , then which one of the following statements is not true?

  1. A For all symmetric matrices \(M\) and \(N, M N-N M\) is skew symmetric
  2. B \(N^{\top} M N\) is symmetric or skew symmetric according as \(M\) is symmetric or skew symmetric
  3. C For all symmetric matrices \(M\) and \(N\), matrix \(M N\) is symmetric
  4. D For any two matrices \(M\) and \(N\), adj \((M N)\) and adj (NM) need not be equal
Verified Solution

Answer & Solution

Correct Answer

(C) For all symmetric matrices \(M\) and \(N\), matrix \(M N\) is symmetric

Step-by-step Solution

Detailed explanation

For two square matrices \(M\) and \(N\) of order 3 , the matrix \(M N-N M\) is skew symmetric, if \(M\) and \(N\) are symmetric matrices, because \(\begin{aligned} & (M N-N M)^T=(M N)^T-(N M)^T \\ & =N M-M N=-(M N-N M)\end{aligned}\) The matrix \(N^T M N\) is symmetric or skew…