Đáp án:
`(4^5 . 9^4 - 2.6^9)/(2^10 . 3^8 + 6^8 . 20)`
`= ((2^2)^5 . (3^2)^4 - 2.(2.3)^9)/(2^10 . 3^8 + (2.3)^8 . 2^2 .5)`
`= (2^10 . 3^8 - 2.2^9 . 3^9)/(2^10 . 3^8 + 2^8 . 3^8 . 2^2 . 5)`
`= (2^10 . 3^8 - 2^10 . 3^9)/(2^10 . 3^8 + 2^10 . 3^8 . 5)`
`= (2^10 . 3^8 (1 - 3))/(2^10 . 3^8 (1 + 5))`
`= (-2)/6`
`= -1/3`