A B CX X 2 , 1, 3. 3 ( 3)(X 1) 3 9 ( 3)X X X X X A...
Bài 2: A B Cx x
2
, 1, 3. 3 ( 3)(x 1) 3 9 ( 3)x x x x x 12
3 9; 1A C x x B x
2
2
2
3 9; 1A C x x B x 2