Algebra
posted by Amy on .
I don't quite understand how to solve matrices with three variables.
If I have the equations:
7x4y2z=0
2x3y+z=0.25
2x2y+5z=0
How can I solve this? I saw the explanation in a site but I didn't understand it. They appeared to make random operations until the matrix was:
1 0 0
0 1 0
0 0 1
I tried with the equations above but I got stuck no matter which order I had.
Please Help.

THAT IS CALLED GAUSS JORDAN REDUCTION


Here is a calculator
http://www.gregthatcher.com/Mathematics/GaussJordan.aspx 
Step 2: Enter the values for your matrix, and press the "Solve" button.
7 4 2 0
2 3 1 1/4
2 2 5 0
Divide row1 by 7
1 4/7 2/7 0
2 3 1 1/4
2 2 5 0
Add (2 * row1) to row2
1 4/7 2/7 0
0 13/7 11/7 1/4
2 2 5 0
Add (2 * row1) to row3
1 4/7 2/7 0
0 13/7 11/7 1/4
0 22/7 31/7 0
Divide row2 by 13/7
1 4/7 2/7 0
0 1 11/13 7/52
0 22/7 31/7 0
Add (22/7 * row2) to row3
1 4/7 2/7 0
0 1 11/13 7/52
0 0 23/13 11/26
Divide row3 by 23/13
1 4/7 2/7 0
0 1 11/13 7/52
0 0 1 11/46
Add (11/13 * row3) to row2
1 4/7 2/7 0
0 1 0 31/92
0 0 1 11/46
Add (2/7 * row3) to row1
1 4/7 0 11/161
0 1 0 31/92
0 0 1 11/46
Add (4/7 * row2) to row1
1 0 0 6/23
0 1 0 31/92
0 0 1 11/46