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TS EAMCET · Maths · Matrices

Let \(A=\left[\begin{array}{rrr}-1 & -2 & -3 \\ 3 & 4 & 5 \\ 4 & 5 & 6\end{array}\right], B=\left[\begin{array}{cr}1 & -2 \\ -1 & 2\end{array}\right] \quad\) and \(C=\left[\begin{array}{lll}2 & 0 & 0 \\ 0 & 2 & 0 \\ 0 & 0 & 2\end{array}\right]\), if \(a, b\) and \(c\) respectively, denote the ranks of \(A, B\) and \(C\), then the correct order of these number is

  1. A \(a < b < c\)
  2. B \(c < b < a\)
  3. C \(b < a < c\)
  4. D \(a < c < b\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(b < a < c\)

Step-by-step Solution

Detailed explanation

Given, \(A=\left[\begin{array}{rrr}-1 & -2 & -3 \\ 3 & 4 & 5 \\ 4 & 5 & 6\end{array}\right]\) \(\begin{aligned} \therefore|A| & =-1(24-25)+2(18-20)-3(15-16) \\ & =1-4+3=0\end{aligned}\) Now, \(\left|\begin{array}{ll}4 & 5 \\ 5 & 6\end{array}\right|=24-25=-1 \neq 0\)…