Question 924942
x-9y+4z=1 
-2x+9y-4z=-3 
2x+y-4z=-3
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Add 2 times the 1st row to the 2nd row
Subtract 2 times the 1st row from the 3rd row
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x-9y+4z=1 
0-9y+4z=-1 
0+19y-12z=-5
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Add 3 times the 2nd row to the 3rd to get:
x-9y+4z=1 
0-9y+4z=-1 
0-8y=0=-8
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Solve the 3rd equation for "y"::
Add 3 times the 2nd row to the 3rd to get:
x-9y+4z=1 
0-9y+4z=-1 
y = 1
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Substitute y = 1 into the 2nd equation to solve for "z".
x-9y+4z=1 
z = 2 
y = 1
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Solve for "x":
x = 2
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Cheers,
Stan H.
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