... KiÓm tra 1 5 , 6 6 a − + − 4 12 , 13 39 b − + §¸p ¸n 1 5 1 5 1 ( 5) 6 , 1 6 6 6 6 6 6 a − − − − + − − + = + = = = − − 4 12 4.3 12 12 12 12 ( 12) ... tổng bằng 0: 1 1 1 1 1 1 , , ,0, , , 6 3 2 2 3 6 1 1 1 0 2 3 6 + + = Ví dụ. Đáp án 1 1 1 0 2 3 6 + + = 1 1 0 0 2 2 + + = 1 1 0 0 3 3 + + = 1 1 0 0 6 6 + + = Lưu ý: - Chia làm 2 nhóm, mỗi ... 21 6 30 C − − − = + + + §¸p ¸n 2 15 15 8 4 17 17 23 23 19 2 15 15 8 4 ( ) ( ) 17 17 23 23 19 4 ( 1) 1 19 4 4 0 19 19 − − = + + + + − − = + + + + = − + + = + = 1 1 1 1 2 7 3 6 1 1 1 1 ( ) 2 3 6...