My Math Forum  

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

Linear Algebra Linear Algebra Math Forum


Thanks Tree2Thanks
  • 1 Post By Joppy
  • 1 Post By skipjack
Reply
 
LinkBack Thread Tools Display Modes
August 14th, 2018, 10:12 PM   #1
Senior Member
 
Chikis's Avatar
 
Joined: Jan 2012

Posts: 724
Thanks: 7

matrix method for simultaneous equations

I have used matrix method of solving simultaneous equation on these
x + y + z = 5
2x - y + 3z = 16
3x + 2y - z = 3.
All the results I get when substituted into the original equation does not tarry with what is on ground, until I used the old traditional method and got x = -9, y = 2, z = 12,
and substituted the values to the original equations and it worked.
Now my take is that you cannot use matrix method or Cramer rule to solve the equation. If I am lying, prove me wrong. Am ready to learn maybe if I missed something along the line when solving.

Last edited by skipjack; August 15th, 2018 at 01:26 AM.
Chikis is offline  
 
August 15th, 2018, 12:19 AM   #2
Senior Member
 
Joined: Feb 2016
From: Australia

Posts: 1,706
Thanks: 597

Math Focus: Yet to find out.
You might like to play around here. The solutions have working attached.
Thanks from topsquark
Joppy is offline  
August 15th, 2018, 12:44 AM   #3
Math Team
 
topsquark's Avatar
 
Joined: May 2013
From: The Astral plane

Posts: 1,889
Thanks: 767

Math Focus: Wibbly wobbly timey-wimey stuff.
Quote:
Originally Posted by Chikis View Post
I have used matrix method of solving simultaneous equation on these
x + y + z = 5
2x - y + 3z = 16
3x + 2y - z = 3.
All the results I get when substituted into the original equation does not tarry with what is on ground, until I used the old traditional method and got x = -9, y = 2, z = 12,
and substituted the values to the original equations and it worked.
Now my take is that you cannot use matrix method or Cramer rule to solve the equation. If I am lying, prove me wrong. Am ready to learn maybe if I missed something along the line when solving.
Your solution doesn't work. Is there a typo? W|A (here) and I (I verified W|A's result by Cramer's rule) get x = 35/13, y = -12/13, z = 42/13.

-Dan

Last edited by skipjack; August 15th, 2018 at 01:30 AM.
topsquark is online now  
August 15th, 2018, 01:25 AM   #4
Global Moderator
 
Joined: Dec 2006

Posts: 19,703
Thanks: 1804

Quote:
Originally Posted by Chikis View Post
I used the old traditional method and got x = -9, y = 2, z = 12,
and substituted the values to the original equations and it worked.
In that case, your third equation was 3x + 21y - z = 3, not 3x + 2y - z = 3.
Thanks from topsquark
skipjack is online now  
Reply

  My Math Forum > College Math Forum > Linear Algebra

Tags
equation, equations, matrix, method, simultaneous



Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Simultaneous equations. prashantakerkar Algebra 10 May 31st, 2017 12:08 PM
Hello :) (simultaneous equations) Ole Daniel Algebra 3 January 11th, 2015 09:35 PM
Simultaneous Equations... srahman33 Algebra 2 August 28th, 2014 02:55 AM
Simultaneous equations ron246 Algebra 5 May 22nd, 2014 02:33 AM
Simultaneous Equations TauMuon Linear Algebra 1 March 13th, 2014 03:59 PM





Copyright © 2018 My Math Forum. All rights reserved.