Respostas

2013-11-24T12:47:03-02:00
3 [2 (x + y) - 4 (x - y)] =
3 [2x + 2y - 4x + 4y] =
6x + 6y - 12x + 12y =
6x - 12x + 6y + 12y =
- 6x + 18y
2 3 2