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!

Compute (B^T)(C) and multiply the result by A on the right

  1. Sep 30, 2009 #1
    "Compute (B^T)(C) and multiply the result by A on the right"

    1. The problem statement, all variables and given/known data

    I have three 3x1 matrices A, B, and C.

    First I have to multiply (AB^T)C. I understand the result is a 3x1 matrix (I think).

    Next the question says "Compute (B^T)C and multiply the result by A on the right. (Hint: (B^T)C is 1x1).

    The last question is "Explain why (AB^T)C = ((B^T)C)A.

    2. Relevant equations



    3. The attempt at a solution

    I don't understand the second question. Does "multiply the result by A on the right" mean ((B^T)C)A or A((B^T)C)? Because I find that the former is not defined but the latter is.

    But then I got confused because of the last question.

    Can anyone clarify this for me? I'd appreciate it, thanks.
     
  2. jcsd
  3. Sep 30, 2009 #2

    D H

    User Avatar
    Staff Emeritus
    Science Advisor

    Re: "Compute (B^T)(C) and multiply the result by A on the right"

    Multiply X on the right by Y means XY, not YX. As you have discovered, matrix multiplication is not commutative. It is transitive, however.
     
  4. Sep 30, 2009 #3
    Re: "Compute (B^T)(C) and multiply the result by A on the right"

    Thanks a lot!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Compute (B^T)(C) and multiply the result by A on the right
  1. C < a + b (Replies: 3)

  2. A × (b × c) = (Replies: 16)

Loading...