2x +my -3z = 1 4 + m - 3 = 1 m = 0
x + y - z = 2
mx + 2y + z = 3
2x+y - 3z = 1 (1)
x + y - z = 2 (2)
x + 2y + z = 3 (3)
din(2) + (3) ⇒ 2x + 3y = 5 y = (5-2x)/3
din (1) + 3·(3)⇒ 5x +7y = 10 5x +7(5-2x)/3 = 10 15x + 35 - 14x = 30
x = -5 y = 5 z = -5 + 5 - 2 z = -2