Question 1099395
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1)  Since the matrix B is non-degenerated, it has the inverse matrix  {{{B^(-1)}}}.


    Multiply the matrix {{{A*B-I}}} by the matrix {{{B^(-1)}}}  on the right. You will get

    {{{(A*B-I)*B^(-1)}}} = {{{A - B^(-1)}}}.


    Since both matrices on the left side of the equation are non-degenerated, their product on the right side is non-degenerated, too.


    QED
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