Question 1128334
solve by elimination
 x-y-2z =4 --- Eqn 1
-x+2y+z=1  --- Eqn 2
-x+y-3z=11  -- Eqn 3
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Eliminate 1 of the 3 variables.
Start with x, since all 3 coefficients are 1 or -1
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 x-y-2z =4 --- Eqn 1
-x+2y+z=1  --- Eqn 2
------------------------------ Add
y + z = 5 --- Eqn A
---
 x-y-2z =4 --- Eqn 1
-x+y-3z=11  -- Eqn 3
---------------------------- Add
-5z = 15
z = -3
*******************
y + z = 5 --- Eqn A
y - 3 = 5
y = 8
*******************
 x-y-2z =4 --- Eqn 1
x - 8 + 6 = 4
x = 6
(6,8,-3)