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MHT CET · Maths · Matrices

The value of \(x\) such that the matrix \(\left[\begin{array}{lll}x & 2 & 3 \\ 4 & 5 & 6 \\ 2 & 3 & 5\end{array}\right]\) is not invertible is

  1. A \(\frac{-10}{7}\)
  2. B \(\frac{7}{10}\)
  3. C \(\frac{-7}{10}\)
  4. D \(\frac{10}{7}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\frac{10}{7}\)

Step-by-step Solution

Detailed explanation

For given matrix to be invertible, we write
\(\left|\begin{array}{lll}x & 2 & 3 \\ 4 & 5 & 6 \\ 2 & 3 & 5\end{array}\right|=0\)
\(x(25-18)-2(20-12)+3(12-10)=0 \Rightarrow 7 x-\) \(16+6=0 \Rightarrow x=\frac{10}{7}\)