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Math Help - matrices

  1. #1
    Junior Member
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    Exclamation matrices

    hi i need to know -

    how do you find the inverse of matrix B from:
    (I+B)^-1=I-B

    where I is the identity matrix, and B is a 4x4 square matrix.

    B in this case is:
    -7 0 0 8
    -6 5 -4 5
    -4 4 -3 3
    -8 0 0 9

    thanks to anyone who can help
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  2. #2
    Senior Member Peritus's Avatar
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    I think there is something wrong with the info because:
    (I+B)^-1=I-B
    <=> I = (I-B)*(I+B)
    <=> I = I + B -B -B^2
    <=> I = I - B^2
    <=> B^2 = 0
    which means that B is nilpotent and therefore not invertible.
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  3. #3
    MHF Contributor

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    As you can see the given information is inconsistent.
    Attached Thumbnails Attached Thumbnails matrices-m1m.gif  
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