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Question 1797: Using matrices solve the system
x-y+z=17
2x+3y+z=8
-4x+y+5z=-2
Answer by longjonsilver(2297)   (Show Source):
You can put this solution on YOUR website! i cannot do effect matrices here with this software...but write the matrix out, like..
1 -1 1 | x = 17
2 3 1 | y = 8
-4 1 5 | z = -2
basically, you need to make the 2 into a zero on the second row and then the -4 and then the 1, so you have a structure like:
1 -1 1 | x = 17
0 a b | y = d
0 0 c | z = e
then you know that z = e/c, then you find y from row 2 then x from row 1.
As to how you do the manipulation to get the zeros, you need to do some mental arithmetic...multiply the top row by 2, so we have a 2 above the 2 in the second row. These both have + signs therefore SAME signs therefore SUBTRACT row2 from row 1...that is your new row 2 etc etc... tedious as hell, but that is matrices for you.
cheers
Jon.
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