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

  • question_answer
    The inverse of the matrix \[\left[ \begin{matrix}    5 & -2  \\    3 & 1  \\ \end{matrix} \right]\] is[Karnataka CET 2005]

    A) \[\frac{1}{11}\left[ \begin{matrix}    1 & 2  \\    -3 & 5  \\ \end{matrix} \right]\]

    B) \[\left[ \begin{matrix}    1 & 2  \\    -3 & 5  \\ \end{matrix} \right]\]

    C) \[\frac{1}{13}\left[ \begin{matrix}    -2 & 5  \\    1 & 3  \\ \end{matrix} \right]\]

    D) \[\left[ \begin{matrix}    1 & 3  \\    -2 & 5  \\ \end{matrix} \right]\]

    Correct Answer: A

    Solution :

    \[A=\left[ \begin{matrix}    5 & -2  \\    3 & 1  \\ \end{matrix} \right]\] \[|A|\,=11,{{A}_{11}}=1,{{A}_{12}}=-3,{{A}_{21}}=2,{{A}_{22}}=5\] \[{{A}^{-1}}=\frac{1}{11}\left[ \begin{matrix}    1 & 2  \\    -3 & 5  \\ \end{matrix} \right]\].


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