Question

x + y + 2z = 4
2x - 3y + z = 0  
5x - y - z = 3

Answer 1

$ Ola Ma

x + y + 2z = 4    (I)
2x - 3y + z = 0   (II)
5x - y - z = 3      (III)

de (II) vem 
z = -2x + 3y

de (I) vem 
x + y - 4x + 6y = 4
7y - 3x = 4

de (III) vem
5x - y + 2x - 3y = 3
7x - 4y = 3

-3x + 7y = 4
7x - 4y = 3

-21x + 49y = 28
21x - 12y = 9

37y = 37
y = 1

7x - 4 = 3
7x = 7
x = 1

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

S = ( (x,y,z) (1,1,1))

pronto