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Math Help - Evaluate (A+1)(A-I)

  1. #1
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    Evaluate (A+1)(A-I)

    Hi,

    Suppose A+I = \[<br />
 \begin{pmatrix}<br />
  1 & 3 & 4 \\<br />
  -1 & 1 & 3 \\<br />
    -2 & -3 & 1 \\<br />
 \end{pmatrix}<br />
\] evaluate (A+I)(A-I)

    Can I assume that A = \[<br />
 \begin{pmatrix}<br />
  0 & 3 & 4 \\<br />
  -1 & 0 & 3 \\<br />
    -2 & -3 & 0 \\<br />
 \end{pmatrix}<br />
\] ?

    Therefore, can I evaluate (A+I)(A-I) by multiplying these two matricies?: \[<br />
 \begin{pmatrix}<br />
  1 & 3 & 4 \\<br />
  -1 & 1 & 3 \\<br />
    -2 & -3 & 1 \\<br />
 \end{pmatrix}<br />
\] \[<br />
 \begin{pmatrix}<br />
  -1 & 3 & 4 \\<br />
  -1 & -1 & 3 \\<br />
    -2 & -3 & -1 \\<br />
 \end{pmatrix}<br />
\]
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  2. #2
    Behold, the power of SARDINES!
    TheEmptySet's Avatar
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    Yes.
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  3. #3
    Member
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    Quote Originally Posted by TheEmptySet View Post
    Yes.
    Thanks TheEmptySet!
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