Giải giúp mh bài 4 nhé

`ttcolor{orange}{@thuyhien}`

`1)` `15^8 . 9^4`

`= (3 . 5)^8 . (3^2)^4`

`= 3^8 . 5^8 . 3^8`

`= (3 . 5 . 3)^8`

`= 45^8`

`2)` `4^9 : 5^27`

`= 4^9 : (5^3)^9`

`= 4^9 : 125^9`

`= (4 : 125)^9`

`= (4/125)^9`

`3)` `20^10 : 2^20`

`= 20^10 : (2^2)^10`

`= 20^10 : 4^10`

`= (20 : 4)^10`

`= 5^10`

`4)` `27^5 : (-7)^15`

`= (3^2)^5 : (-7)^15`

`= 3^15 : (-7)^15`

`= [3 : (-7)]^15`

`= (-3/7)^15`