... 0 ,25 0,5 0 ,25 −5 × - = x 21 −5 ×x = + 21 −5 + ×x = 21 ×x = 21 × 32 x= = 21 21 3 b) ×x − ×x = 12 ×x ×x − = 12 ×x 18 ×x − = 12 12 0 ,25 0 ,25 0 ,25 0 ,25 0 ,25 0 ,25 ×x − 18 ×x = 12 −13 ×x = 12 −13 12 ... = 100o - 50o = 50o 0 ,25 0 ,25 0 ,25 0 ,25 3.7 + 9 .28 + 15. 42 + 21 . 56 6.14 + 12. 35 + 18 .63 + 30.77 3.7 + (3.3).(4.7) + (5.3). (6. 7) + (7.3).(8.7) = (2. 3). (2. 7) + (4.3).(5.7) + (6. 3).(9.7) + (10.3).(11.7) ... (10.3).(11.7) A= 3.7.(1.1 + 3.4 + 5 .6 + 7.8) 3.7. (2. 2 + 4.5 + 6. 9 + 10.11) 1.1 + 3.4 + 5 .6 + 7.8 = 2. 2 + 4.5 + 6. 9 + 10.11 99 = 188 = Tổng 0 ,25 0 ,25 0 ,25 0 ,25 10 điểm Ghi chú: Trên định hướng...