JEE Main & Advanced Mathematics Determinants & Matrices Question Bank Special types of matrices, Transpose, Adjoint and Inverse of matrices

  • question_answer
    If \[A=\left[ \begin{matrix}    2 & 3  \\    4 & 6  \\ \end{matrix} \right]\], then \[{{A}^{-1}}\]= [Karnataka CET 2001]

    A) \[\left[ \begin{matrix}    1 & 2  \\    -3/2 & 3  \\ \end{matrix} \right]\]

    B) \[\left[ \begin{matrix}    2 & -3  \\    4 & 6  \\ \end{matrix} \right]\]

    C) \[\left[ \begin{matrix}    -2 & 4  \\    -3 & 6  \\ \end{matrix} \right]\]

    D) Does not exist

    Correct Answer: D

    Solution :

    Given,\[A=\left[ \begin{matrix}    2 & 3  \\    4 & 6  \\ \end{matrix} \right]\], we know that \[{{A}^{-1}}=\frac{adj.A}{|A|}\]. Therefore, \[|A|\,\,=\,\,[12-12]=0.\] Since \[|A|\] is zero, therefore inverse of A does not exist.


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