My Math Forum  

Go Back   My Math Forum > High School Math Forum > Algebra

Algebra Pre-Algebra and Basic Algebra Math Forum

LinkBack Thread Tools Display Modes
June 24th, 2010, 04:23 PM   #1
Joined: Jun 2010

Posts: 24
Thanks: 0


If I was given a 4x5 matrix B and a 5x4 matrix A, what are the dimensions of BA?

Is it 5x5 or 4x4 or BA is not defined? thanks
bignick79 is offline  
June 24th, 2010, 05:21 PM   #2
Global Moderator
The Chaz's Avatar
Joined: Nov 2009
From: Northwest Arkansas

Posts: 2,766
Thanks: 4

Re: Dimensions

Write the dimensions from left to right.
i.e. 4x5 by 5x4.
For the resulting matrix to be defined, the inner dimensions must be equal. 5=5... check.
The outer dimensions (from left to right) are the resulting dimensions. 4x4.

To generalize, a CxD matrix times a DxE matrix
has dimensions CxE.
The Chaz is offline  

  My Math Forum > High School Math Forum > Algebra


Search tags for this page
Click on a term to search for related topics.
Thread Tools
Display Modes

Similar Threads
Thread Thread Starter Forum Replies Last Post
Sum of dimensions of eigenspaces Virus Linear Algebra 1 September 9th, 2011 07:08 AM
Dimensions MattJ81 New Users 3 July 27th, 2011 11:40 PM
VC dimensions redandtheblue Applied Math 0 February 15th, 2009 11:07 AM
Patio Dimensions symmetry Algebra 5 January 30th, 2007 02:51 AM

Copyright © 2019 My Math Forum. All rights reserved.