Question

Resolva o sistema :
{ x+2y - z = 0
{2x + y + z = 3

Answer 1

x = z - 2y

2(z - 2y) + y + z = 3
2z - 4y + y + z = 3
3z - 3y = 3
z - y = 1(-1)
y + z = -3

2x + y + z = 3
2x -3 = 3
2x = 6
x = 3

3 + 2y - z = 0
6 + y  + z = 3
___________
9 + 3y = 3
3y = -6
y = -2

x + 2y - z = 0
3 - 4 - z = 0
-z = 4 - 3
-z = 1 
z = -1