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Homework Help: Multiplying a determinant by a constant? book says

  1. Oct 16, 2005 #1
    I'm confused, this question had 5 parts and i got the other 4 but this one I keep missing...
    If A is a 2x2 matrix....
    Det(A) = -5;
    The Det(-3A);
    The book said, if u multiply a column by a constant k then the determinant is also multiplied by k. So wouldn't the answer just be (-5)(-3) = 15?
    Det(-3A) = 15? it says its wrong htough...:bugeye:
  2. jcsd
  3. Oct 16, 2005 #2


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    Evaluate [tex]\left|\begin{array}{cc} ka& kb \\ kc&kd\end{array}\right| [/tex]... and compare it to [tex]\left|\begin{array}{cc} a& b \\ c&d\end{array}\right| [/tex]. Next try the 3x3 case.
    Last edited: Oct 16, 2005
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