`(2x-1)^2 - 2|2x-1| + 1 = 0`
$\\$ ` \Leftrightarrow (|2x-1|)^2 - 2|2x-1| + 1 = 0`
$\\$ ` \Leftrightarrow (|2x-1| - 1)^2 = 0`
$\\$ ` \Leftrightarrow |2x-1| - 1 = 0`
$\\$ ` \Leftrightarrow |2x-1| = 1`
$\\$ ` \Leftrightarrow [(2x - 1 = 1 ),(2x-1 = -1 ):} \Leftrightarrow [(2x = 2 ),(2x = 0 ):} \Leftrightarrow [(x = 1 ),(x = 0 ):}`
$\\$ ` Vậy : S = {1;0}`
