1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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

    robphy

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    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
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook