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Giải thích các bước giải:

`2/3x - 5/6 = 3/5`

`2/3x = 3/5 + 5/6`

`2/3x = 18/30 + 25/30`

`2/3x = 43/30`

`x = 43/30 : 2/3`

`x = 43/30 . 3/2`

`x = 43/20`

Vậy `x=43/20`

`-----`

`b) 3/4 + 1/4 : x = 2/5`

`1/4 : x = 2/5 - 3/4`

`1/4 : x = 8/20 - 15/20`

`1/4 : x = (-7)/20`

`x = 1/4 : (-7)/20`

`x = 1/4 . (-20)/7`

`x = (-5)/7`

Vậy `x=-5/7`

`-----`

`c) ( x - 1/3 )^2 = 16/25`

`( x - 1/3 )^2 = (4/5)^2` hoặc `( x - 1/3)^2 = (-4/5)^2`

`x - 1/3 = 4/5` hoặc `x - 1/3 = -4/5`

`x = 4/5 + 1/3` hoặc `x = -4/5 + 1/3`

`x = 12/15 + 5/15` hoặc `x = -12/15 + 5/15`

`x =17/15` hoặc `x = -7/15`

Vậy `x ∈ { 17/15; -7/15 }`

`-----`

`d) ( 2x - 3 )^3 = -27`

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

`2x - 3 = -3`

`2x = -3 + 3`

`2x = 0`

`x = 0 :2`

`x = 0`

Vậy `x=0`

`#By.`