Đáp án:
Giải thích các bước giải:
$\sqrt{4x^2 -4x +1}=|-2|$
$⇔\sqrt{(2x)^2 -2.2x. 1 +1^2}=2$
$⇔\sqrt{(2x-1)^2}=2$
`⇔|2x-1|=2`
`⇔ 2x-1 = ±2`
`⇔`\(\left[ \begin{array}{l}2x-1=2\\2x-1=-\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}2x=3\\2x=-1\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=\dfrac{3}{2}\\x=\dfrac{-1}{2}\end{array} \right.\)
vậy `S={ 3/2 ; -1/2 }`
