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 Post subject: Needing help with Systems of Equations with three variables.Posted: Fri, 24 Sep 2010 03:27:49 UTC
 S.O.S. Newbie

Joined: Fri, 24 Sep 2010 02:44:59 UTC
Posts: 2
I'm lost on how to complete them using matrices. It would be nice to have a step by step explanation if it's possible. The guide that was available on the site had a different way than what my professor tried to show. And the guide on the site was VERY simple, it didn't help with the problems that I was assigned. (Notably the first row, it was just all 1's and didn't help all that much.)

Ex.
2x + 6y + 3z = -20
5x - 3y - 5z = 47
4x + 3y + 2z = 4

The site had me try to get the Matrix to look something like this...
| 1 0 0 : a |
| 0 1 0 : b |
| 0 0 1 : c |

As my professor wanted just wanted it to look something like this...
| 1 * * : * |
| 0 1 * : * |
| 0 0 1 : * |
Where * is any number. (Not sure if it has to be any real number or not)

I'm not sure what to work on, especially since I just end up getting my work wrong because I end up working on it too much. But for the most part I just need to understand the steps into it.

(Didn't see the matrix algebra section until just now... please move this there.)

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 Post subject: Posted: Fri, 24 Sep 2010 03:48:50 UTC
 Senior Member

Joined: Fri, 3 Sep 2010 09:29:45 UTC
Posts: 140
That is just the difference between row echelon and reduced row echelon form.

Once you have row echelon form it is easy to get to reduced form (as you essential already know one of x,y,z)

This is just Gauss-Jordan elimination - a quick google should help out

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 Post subject: Re: Needing help with Systems of Equations with three variabPosted: Fri, 24 Sep 2010 04:33:34 UTC
 Member of the 'S.O.S. Math' Hall of Fame

Joined: Sun, 24 Jul 2005 20:12:39 UTC
Posts: 3693
Location: Ottawa Ontario
KnightKilo wrote:
2x + 6y + 3z = -20
5x - 3y - 5z = 47
4x + 3y + 2z = 4

Do you know how to solve these by elimination or substitution?

_________________
I'm not prejudiced...I hate everybody equally!

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 Post subject: Re: Needing help with Systems of Equations with three variabPosted: Fri, 24 Sep 2010 05:07:36 UTC
 S.O.S. Newbie

Joined: Fri, 24 Sep 2010 02:44:59 UTC
Posts: 2
Denis wrote:
Do you know how to solve these by elimination or substitution?

Yes, I do. But the problems is REQUIRED to be solved using the Matrix method mainly.

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