x+2y=0
x+3y+z=1
-4x-y-z=23
x + 2 y = 0 Subtract 2 y to both sides
x + 2 y - 2 y = 0 - 2 y
x = - 2 y
x + 2 y = 0
+
x + 3 y + z = 1
+
- 4 x - y - z = 23
___________________
- 2 x + 4 y = 24
- 2 * ( - 2 y ) + 4 y = 24
4 y + 4 y = - 24
8 y = 24 Divide both sides by 8
y = 24 / 8 = 3
x = - 2 y = - 2 * 3 = - 6
x + 3 y + z = 1
- 6 + 3 * 3 + z = 1
- 6 + 9 + z = 1
3 + z = 1 Subtract 3 to both sides
3 + z - 3 = 1 - 3
z = - 2
The solutions are:
x = - 6 , y = 3 , z = -2