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!

Determinant math homework

  1. Feb 6, 2014 #1
    1. The problem statement, all variables and given/known data
    Determinant
    |a b c|
    |d e f| = 5
    |g h i|
    What is the determinant of?
    |4a 4b 4c|
    |3d 3e 3f|
    | g h i|

    3. The attempt at a solution
    So far I got this, a(ei - hf) - b(di - gf) + c(dh - ge) = 5
    How would I even go about this, I have 9 unknowns, but only 1 equations?
     
  2. jcsd
  3. Feb 6, 2014 #2

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    Determinants have properties that are related to row operations. Look some of them up. You don't have to explicitly evaluate the determinants.
     
  4. Feb 6, 2014 #3
    Which row operations, I am looking in my textbook and it gives no information on this topic.
     
  5. Feb 6, 2014 #4

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    Ok, try here. http://science.kennesaw.edu/~plaval/math3260/det2.pdf [Broken]. What happens to the determinant of a matrix when you multiply a row by a constant?
     
    Last edited by a moderator: May 6, 2017
  6. Feb 6, 2014 #5

    Ray Vickson

    User Avatar
    Science Advisor
    Homework Helper

    Google is your friend.
     
  7. Feb 6, 2014 #6

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    Ack! You revealed my secret. Yes, I typed "row operations determinants" into Google.
     
  8. Feb 6, 2014 #7
    Ohh, so if I factore out the 3 and the 4 I would get 12 det(A) where A is the first matrix, then 12 det(A) = 60, oh ok thanks. And Ray, I wouldn't know what to google.
     
  9. Feb 6, 2014 #8

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    Actually, I think I just did "determinant properties". It's not an obscure fact about determinants. Probably in your textbook someplace.
     
  10. Feb 6, 2014 #9

    Ray Vickson

    User Avatar
    Science Advisor
    Homework Helper

    You want to know more about determinants, so Google 'determinant'.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Determinant math homework
  1. Indices math homework (Replies: 2)

Loading...