hẹp hẹp hẹp vvvvvv.vvv

`a) (1/3)^7 : (1/3)^x = (1/3)^6`

`=> 7 - x = 6`

`=> x = 7 -6`

`=> x = 1`

Vậy `x=1`

`b) (2/5)^(x+1) : 2/5 = 4/25`

`=> (2/5)^(x+1) : (2/5)^1 = (2/5)^2`

`=> x + 1 - 1 = 2`

`=> x = 2`

Vậy `x=2`

`c) (0,25)^5 : (1/4)^(x+3) = 1/16`

`=>(1/4)^5 : (1/4)^(x+3) = (1/4)^2`

`=> 5 - (x+3) = 2`

`=> 5 - x - 3 = 2`

`=> 2 - x = 2`

`=> x = 2-2`

`=> x=0`

Vậy `x=0`

`d) 3^4 - (x+1)^2 = 17`

`=> 81 - (x+1)^2 = 17`

`=> (x+1)^2 = 81 - 17`

`=> (x+1)^2 = 64`

`=> (x+1)^2 = (+-8)^2`

`=>` \(\left[ \begin{array}{l}x+1 = 8\\x+1=-8\end{array} \right.\) 

`=>` \(\left[ \begin{array}{l}x= 8 -1\\x=-8-1\end{array} \right.\) 

`=>` \(\left[ \begin{array}{l}x= 7\\x=-9\end{array} \right.\) 

Vậy `x in {7;-9}`

`#HPHG`