ExamBro
ExamBro
AP EAMCET · Maths · Matrices

Let \(M\) and \(N\) be two matrices over \(R\) of order 2. Then, \(M N=N M\) if .......

  1. A One of \(M\) and \(N\) is a diagonal matrix
  2. B Both \(M\) and \(N\) are diagonal matrices
  3. C Both \(M\) and \(N\) are invertible matrices
  4. D None of these options are true in general
Verified Solution

Answer & Solution

Correct Answer

(B) Both \(M\) and \(N\) are diagonal matrices

Step-by-step Solution

Detailed explanation

Let \(M=\left(\begin{array}{ll}a & b \\ c & d\end{array}\right), N=\left(\begin{array}{ll}p & q \\ r & s\end{array}\right)\) Then, \(\quad M N=\left(\begin{array}{ll}a p+b r & a q+b s \\ p c+d r & c q+d s\end{array}\right)\) and…