My Math Forum  

Go Back   My Math Forum > College Math Forum > Linear Algebra

Linear Algebra Linear Algebra Math Forum

LinkBack Thread Tools Display Modes
June 3rd, 2014, 11:24 AM   #1
Joined: Nov 2013

Posts: 47
Thanks: 4

Determinant proof for 3 by 3 matrices

To get the determinant of 3 by 3 matrices we're told to just reduce the 3 by 3 matrix into three 2 by 2s by essentially taking 3 terms in the matrix and eliminating their column and row and then multiplying those terms by their respective 2 by 2 sub-matrices. I'm able to use the method, but I don't like blindly applying methods like this without having at least some intuition of why they work. I've looked at a geometric proof for why the determinant of a 2 by 2 matrix is ad-bc and it makes sense, but I havent been able to find a proof for the method that I described above. Why in the world does that work?
Orlando895 is offline  
June 4th, 2014, 08:18 PM   #2
Joined: Jun 2014
From: USA

Posts: 21
Thanks: 2

It is possible by multiplication only there is not any other option to change 3 by 3 matrix in 2 by 2.
peterwilliam is offline  

  My Math Forum > College Math Forum > Linear Algebra

determinant, matrices, proof

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
general formula for determinant(matrices) ungeheuer Linear Algebra 1 August 31st, 2013 02:15 PM
Matrices, proof OliverRunner Linear Algebra 2 January 25th, 2013 11:22 AM
square matrix determinant proof help! Linear Algebra 1 December 15th, 2012 07:54 AM
Determinant of PD matrices thedinuka Linear Algebra 3 August 10th, 2012 05:37 AM
determinant for matrices serenaxiuli Algebra 0 April 11th, 2009 07:11 AM

Copyright © 2019 My Math Forum. All rights reserved.