... SGK:a) (27 + 65 ) + (3 46 - 27 - 65 ) = 27 + 65 + 3 46 - 27 - 65 = (27 -27 )+ (65 -65 ) + 3 46 = 3 46 b) ( 42 - 69 +17) - ( 42 + 17) = 42 - 69 + 17 - 42 - 17 = ( 42- 42) + (17-17) - 69 = - 69 Bài 92 /65 SBT:a) ... 3 2 + 2 2. 2 3= 3 2 + 2 5 = 9 + 32 = 41c/ 92 - {[ ( 22 4 + 1 36 ) : 30] . 5} = 92 - {[ 360 : 30] . 5}= 92 - { 12 . 5} = 92 - 60 = 32 Bi 2: Tỡm s t nhiờn x bit:a/ x - 130 = 2 46 x = 2 46 + ... 7. 22 + 78 . 7 = 7. (22 + 78) = 7 . 100 = 700b/ 34 : 3 2 + 2 2. 2 3= 3 2 + 2 5 = 9 + 32 = 41c/ 92 - {[ ( 22 4 + 1 36 ) : 30] . 5} = 92 - {[ 360 : 30] . 5}= 92 - { 12 . 5} = 92 - 60 = 32 0,5...