`a) 73^2 - 27^2`
`= (73 + 27)(73 - 27)`
`= 100 . 46`
`= 4600`
`b) 63^2 - 27^2 + 72^2 - 18^2`
`= (63 - 27)(63 + 27) + (72 - 18)(72 + 18)`
`= 36 . 90 + 54 . 90`
`= 8100`
`c) `105^3 - 15.105^2 + 75.105 - 125`
`=105^3 - 3.105^2.5 + 3.105.5^2 - 5^3`
`=(105 - 5)^3`
`=100^3`
`= 1000000` (check hộ mình xem đủ sáu số 0 chưa ạ)
`d) (68^3 - 32^3)/36 + 68.32`
`= ((68-32)(68^2 + 68.32 + 32^2)) / 36 + 68.32`
`= 68^2 + 68 . 32 + 32^2 + 68.32`
`= (68+32)^2`
`=100^2`
`=10000`