Đáp án`+`Giải thích các bước giải:

 `1) (2x-1)^3=8/27`

`(2x-1)^3=(2/3)^3`

`2x-1=2/3`

`2x=2/3+1`

`2x=5/3`

`x=5/3:2`

`x=5/6`

Vậy `x=5/6`

`4) (2x+1)^2=16/25`

`(2x+1)^2=(+-4/5)^2`

`th1:`

`2x+1=4/5`

`2x=4/5-1`

`2x=-1/5`

`x=-1/5:2`

`x=-1/10`

`th2:`

`2x+1=-4/5`

`2x=-4/5-1`

`2x=-9/5`

`x=-9/5:2`

`x=-9/10`

Vậy `x∈{-1/10;-9/10}`

`7) (1-2/3x)^2=4/9`

`(1-2/3x)^2=(+-2/3)^2`

`th1:`

`1-2/3x=2/3`

`2/3x=1-2/3`

`2/3x=1/3`

`x=1/3:2/3`

`x=1/2`

`th2:`

`1-2/3x=-2/3`

`2/3x=1+2/3`

`2/3x=5/3`

`x=5/3:2/3`

`x=5/2`

Vậy `x∈{1/2;5/2}`

`10) 3.(x-1/2)^3 =81`

`(x-1/2)^3=81:3`

`(x-1/2)^3=27`

`(x-1/2)^3=3^3`

`x-1/2=3`

`x=3+1/2`

`x=7/2`

Vậy `x=7/2`

`13) (2/3-x)^2=1:4/9`

`(2/3-x)^2=9/4`

`(2/3-x)=(+-3/2)^2`

`th1:`

`2/3-x=3/2`

`x=2/3-3/2`

`x=-5/6`

`th2:`

`2/3-x=-3/2`

`x=2/3+3/2`

`x=13/6`

Vậy `x∈{-5/6;13/6}`