Bài 28:

`a)`

`4^x = 8^4`

`(2^2)^x = (2^3)^4`

`2^(2x) = 2^12`

`2x = 12`

`x = 6`

Vậy `x = 6`

`b)`

`4^x = 32^24`

`(2^2)^x = (2^5)^24`

`2^(2x) = 2^120`

`2x = 120`

`x = 60`

Vậy `x = 60`

`c)`

`8^x = 16^12`

`(2^3)^x = (2^4)^12`

`2^(3x) = 2^48`

`3x = 48`

`x = 16`

Vậy `x = 16`

`d)`

`4^x = 8^12`

`(2^2)^x = (2^3)^12`

`2^(2x) = 2^36`

`2x = 36`

`x = 18`

Vậy `x = 18`

`e)`

`4^x = 32^40`

`(2^2)^x = (2^5)^40`

`2^(2x) = 2^200`

`2x = 200`

`x = 100`

Vậy `x = 100`

`f)`

`8^x = 32^9`

`(2^3)^x = (2^5)^9`

`2^(3x) = 2^45`

`3x = 45`

`x = 15`

Vậy `x = 15`

`g)`

`8^x = 16^99`

`(2^3)^x = (2^4)^99`

`2^(3x) = 2^396`

`3x = 396`

`x = 132`

Vậy `x = 132`

`h)`

`8^x = 32^33`

`(2^3)^x = (2^5)^33`

`2^(3x) = 2^165`

`3x = 165`

`x = 55`

Vậy `x = 55`

`i)`

`8^x = 32^66`

`(2^3)^x = (2^5)^66`

`2^(3x) = 2^330`

`3x = 330`

`x = 110`

Vậy `x = 110`

`j)`

`16^x = 32^8`

`(2^4)^x = (2^5)^8`

`2^(4x) = 2^40`

`4x = 40`

`x = 10`

Vậy `x = 10`

`k)`

`32^x = 16^10`

`(2^5)^x = (2^4)^10`

`2^(5x) = 2^40`

`5x = 40`

`x = 8`

Vậy `x = 8`

`l)`

`16^x = 64^10`

`(2^4)^x = (2^6)^10`

`2^(4x) = 2^60`

`4x = 60`

`x = 15`

Vậy `x = 15`