<PRE><B>Question 745505</B>
x + 2y + z = 7...............1
3x - y + z = -12..............2
4x + 3y -2z = 9...............3
eqn 2 X 2+eqn 1
x + 2y + z = 7...............1
6x - 2y + 2z = -24..............3
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7x      +3z  =-17.............5

eqn 2X 3 +eqn 3
9x -3y +3z = -36..............6
4x + 3y -2z = 9...............3
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13x     +z=-27..............7

eq5 - eqn 7 X 3
7x  +3z  =-17.............5
39x +3z=-81..............9
-    -  +
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-32x=64
or x=-2

from eqn 5
7*(-2)+z=-17
or z=-17+14=-3

from eqn 1
-2 + 2y -3 = 7.
or 2y=7+5=12
or y=6




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