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Homework Help: Lower triangular matrix

  1. Mar 28, 2010 #1
    1. The problem statement, all variables and given/known data
    I keep trying to turn a 4x4 matrix into a lower triangular matrix and then multiply along the diagonal to get the determinant , but I cant get the answer in the back of the book , is there some property about determinates I am missing .
     
  2. jcsd
  3. Mar 28, 2010 #2

    Mark44

    Staff: Mentor

    Hard to say without seeing your work.

    BTW, the word is determinant.
     
  4. Mar 28, 2010 #3
    ok as long as we add rows together it doesn't change the det(A)
    i can go 5R1+R2=R2 and it wont change the det(A) correct.
     
  5. Mar 28, 2010 #4

    Mark44

    Staff: Mentor

    Right. Of the three row operations, the only ones that change the value of the determinant are replacing a row by a multiple of itself (Rn <-- k*Rn) and switching two rows (Rn <--> Rm).
     
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