`b)`
`| x^2 + 2|x - 1/2|| = x^2 + 2`
`⇔ x^2 + 2|x - 1/2| = x^2 + 2`
`⇔ 2|x - 1/2| = 2`
`⇔ |x - 1/2| = 1`
⇒\(\left[ \begin{array}{l}x=3/2\\x=-1/2\end{array} \right.\)
Vậy `S = {3/2 ; -1/2}`
`c)`
`|x^2 . |x + 3/4|| = x^2`
`⇔ x^2 . |x + 3/4| = x^2`
`⇒| x + 3/4| = 1`
⇒\(\left[ \begin{array}{l}x=1/4\\x=-7/4\end{array} \right.\)
Vậy `S = {1/4 ; -7/4}`