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

  • question_answer
    The inverse of  a symmetric matrix is

    A) Symmetric

    B) Skew symmetric

    C) Diagonal matrix

    D) None of these

    Correct Answer: A

    Solution :

    Let A be a symmetric matrix. Then \[A{{A}^{-1}}=I\Rightarrow {{(A{{A}^{-1}})}^{T}}=I\] \[\Rightarrow \] \[{{({{A}^{-1}})}^{T}}{{A}^{T}}=I\Rightarrow {{({{A}^{-1}})}^{T}}={{({{A}^{T}})}^{-1}}\] \[\Rightarrow \] \[{{({{A}^{-1}})}^{T}}={{(A)}^{-1}}\] , \[(\because \,\,{{A}^{T}}=A)\] \[\Rightarrow \] \[{{A}^{-1}}\] is a symmetric matrix.


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