Решите систему уравнений : х+2у+3z=5;2x-y-z=1;x+3y+4z=6

 x + 2y + 3z = 5 2x - y - z = 1 x + 3y + 4z = 6 ----------------------- x - 3y - 4z = - 6 - y - z = - 1 y = 1 - z-----------------------2x - y - z = 1 2x = 1 + y + z 2x = 1 + 1 - z + z 2x = 2 x = 1 -------------------------x + 2y + 3z = 5 1 + 2( 1 - z ) + 3z = 5 1 + 2 - 2z + 3z = 5 z = 5 - 3 z = 2 ----------------------------y = 1 - z y = 1 - 2 y = - 1 ---------------------------ОТВЕТ x = 1 ; y = - 1 ; z = 2