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Math Help - invertable Matrix's

  1. #1
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    invertable Matrix's

    1) a)Suppose that A is a square matrix of size n*n such that A^2011 = 0. Show that
    the matrix A+In is invertible and find an expression for (A + In)^-1 in terms of A.
    (In is a identity matrix with n*n dimensions)

    b) Let A be a matrix of size 50 *49 and B a matrix of size 49* 50 matrix. Show that
    the matrix AB is not invertible. Give an example of matrices A and B for which BA
    is invertible

    Can I get some help with there questions please? Having a hard time getting my head around them
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  2. #2
    Super Member girdav's Avatar
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    a) Compute for N\in\mathbb{N}^* (A+I_n)\sum_{j=0}^N(-1)^j A^j.
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