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Question about square matrix

  1. Feb 26, 2006 #1
    So i have the following question
    a) Show that if AB and BA are both defined, then AB and BA are square matrices..
    this is what i tried doing..
    If AB and BA are both tdefined then
    A=[n x p ] matrix
    B=[p x l ] matrix
    AB=[nxl] matrix
    IF and only IF l=n, then BA will be defined.
    then BA=[p x p] matrix
    AB=[l x l] matrix
    then by definition both AB and BA will be square matrices..
    is this correct? i think it is wrong.
  2. jcsd
  3. Feb 26, 2006 #2


    User Avatar
    Science Advisor

    That's correct.
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