1. Not finding help here? Sign up for a free 30min 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!

Finding the trace of the inverse of a 2x2 matrix in (mod 26)

  1. Oct 31, 2014 #1
    1. The problem statement, all variables and given/known data
    .......(2 , 3)
    A =
    ......(1 , 3)

    Find the trace of A^(-1)
    2. Relevant equations
    (a , b)................................(d , -b)
    .........^(-1) = (ad-bc)^(-1)*
    (c , d).................................(-c, a)

    3. The attempt at a solution
    ..............(3 , -3)
    A^-1 = 9*
    ..............(-1. 2)

    (In mod 26)

    ........... (1, -1)
    =
    .......... (-9, 18)

    Trace of A^(-1) = 1 + 18 = 19


    The solution I was given said the trace is 18 but I can't seem to find where I went wrong.
    Any help would be appreciated.
    (Also sorry about the horrible way I wrote the matrices)
     
  2. jcsd
  3. Oct 31, 2014 #2

    RUber

    User Avatar
    Homework Helper

    I don't see any issue with what you have. You can verify that your solution is the inverse, so it may be that the solution is off.
     
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: Finding the trace of the inverse of a 2x2 matrix in (mod 26)
Loading...