Question 1004970
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Solve the system

x - y + z =  0   (1)
x + y + z = -2   (2)
x + y - z =  8   (3)

This system is special. It is possible to solve it using the mental math only.

Distract first equation from the second ((1) from (2)). You will get

2y = -2.  Hence,  y = -1.

Next, distract equation (3) from (2). You will get

2z = -10.  Hence,  z = -5.

Finally, substitute the found values y= -1 and z= -5 into the first equation. You will get

x - (-1) + (-5) = 0,   or   x = 5 - 1 = 4.

<U>Answer</U>.  The solution is  x= 4, y= -1 and z= -5.
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