Question 121110
 2X+ Y-3Z =0
-2X+2Y+Z =-7
  X-4Y-3Z =7 
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Put #3 in the #1 position:
 X-4Y-3Z =7
2X+ Y-3Z =0
-2X+2Y+Z =-7
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Subtract twicd #1 from #2; Add twice #1 to #3 to get:
 X-4Y-3Z =7
 0+9y+3Z =-14
 0-6Y-5Z = 7
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Add #3 to #2 to get:
 X-4Y-3Z =7
 0+3y-2Z =-7
 0-6Y-5Z = 7
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Add twice #2 to #3 to get:
 X-4Y-3Z = 7
 0+3y-2Z =-7
 0+ 0-9Z =-7
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Divide thru #3 by -9 to get:
X-4Y-3Z = 7
 0+3y-2Z =-7
 0+ 0+Z = 7/9
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Substitute that value of Z into #2 to solve for Y.
Then substitute the Z value and the Y value into #1 to solve for X.
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I get :
X = 2.0741
Y = -1.8148 
Z = 0.7778= 7/9

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Cheers,
Stan H.