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 August 14th, 2018, 10:12 PM #1 Senior Member   Joined: Jan 2012 Posts: 745 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. August 15th, 2018, 12:19 AM #2 Senior Member   Joined: Feb 2016 From: Australia Posts: 1,838 Thanks: 653 Math Focus: Yet to find out. You might like to play around here. The solutions have working attached. Thanks from topsquark August 15th, 2018, 12:44 AM   #3
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Quote:
 Originally Posted by Chikis 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. August 15th, 2018, 01:25 AM   #4
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Quote:
 Originally Posted by Chikis 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. Tags equation, equations, matrix, method, simultaneous Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Threads Thread Thread Starter Forum Replies Last Post prashantakerkar Algebra 10 May 31st, 2017 12:08 PM Ole Daniel Algebra 3 January 11th, 2015 09:35 PM srahman33 Algebra 2 August 28th, 2014 02:55 AM ron246 Algebra 5 May 22nd, 2014 02:33 AM TauMuon Linear Algebra 1 March 13th, 2014 03:59 PM

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