Question 92859
The soultion to the system of equations below is:
Eq1: x + 2y - z =-3, 
Eq2:2x - y + 3z =14, 
Eq3: x +4y - 2z = 8
:
Multiply eq1 by -2 and add to eq3
-2x - 4y + 2z = 6
  x + 4y - 2z = 8
-------------------adding eliminates y & z
 -x  +0y + 0z = 14
x = -14
:
Add all three equations, eliminates z
 x + 2y - z =-3, 
2x - y + 3z =14, 
 x +4y - 2z = 8
--------------------
4x + 5y + 0z = 19
4x + 5y = 19
:
x = -14, substitute -14 for x in the above and find
4(-14) + 5y = 19
-56 = 5y = 19
5y = 19 + 56
5y = 75
y = 75/5
y = +15
:
I'll let you find z; check solutions in one of the original equations