Question 687929
x+2y+z=10
2x-y+3z=-5
2x-3y-5z=27 
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Subtract 2*1st row from 2nd
Subtract 2*1st row from 3rd
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x+2y+z=10
0x -5y +z = -25
0x -7y -7z = 7
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Multiply 2nd by 7
Multiply 3rd by 5
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x+2y+z=10
0x -35y + 7z = -175
0x -35y -35z =  35
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Subtract 2nd from 3rd to get:
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x+2y+z=10
0x -15y +10z = -75
0x + 0y -42z = 210
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Solve for "z":
z = -5
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Substitute into 2nd and solve for "y"
y = 4
Substitute z and y into 1st and solve for "x"
x = 7
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cheers,
Stan H.