Bỏ dấu ngoặc rồi tính :
\(\eqalign{ & a)\;\left( {4 + 32 + 6} \right) + \left( {10 – 36 – 6} \right) \cr & b)\;\left( {77 + 22 – 65} \right) – \left( {67 + 12 – 75} \right) \cr & c) – \left( { – 21 + 43 + 7} \right) – \left( {11 – 53 – 17} \right). \cr} \)
\(\eqalign{ & a)\left( {4 + 32 + 6} \right) + \left( {10 – 36 – 6} \right) \cr&= 4 + 32 + 6 + 10 – 36 – 6 \cr & = (4 + 32 – 36) + 10 + (6 – 6) \cr&= (36 – 36) + 10 + 0 \cr&= 0 + 19 = 10 \cr & b)\left( {77 + 22 – 65} \right) – \left( {67 + 12 – 75} \right) \cr&= 77 + 22 – 65 – 67 – 12 + 75 \cr & = (77 – 67) + (22 – 12) + (75 – 65) \cr&= 10 + 10 + 10 = 30 \cr & c) – \left( { – 21 + 43 + 7} \right) – \left( {11 – 53 – 17} \right) \cr&= 21 – 43 – 7 – 11 + 53 + 17 \cr & = (21 – 11) + (53 – 43) + (17 – 7) \cr&= 10 + 10 + 10 = 30 \cr} \)