4 · (x-1/2) ² -1 = 0

$\text{4(x - $\dfrac{1}{2}$)² - 1 = 0}$

$\text{4(x - $\dfrac{1}{2}$)² = 1}$

$\text{(x - $\dfrac{1}{2}$)² = $\dfrac{1}{4}$}$

$\text{(x - $\dfrac{1}{2}$)² = (±$\dfrac{1}{2}$)²}$

$\text{⇒ x - $\dfrac{1}{2}$ = ± $\dfrac{1}{2}$}$

$\text{⇒ x - $\dfrac{1}{2}$ = $\dfrac{1}{2}$ hoặc x - $\dfrac{1}{2}$ = -$\dfrac{1}{2}$}$

$\text{TH1: x - $\dfrac{1}{2}$ = $\dfrac{1}{2}$}$

$\text{x = $\dfrac{1}{2}$ + $\dfrac{1}{2}$}$

$\text{x = $\dfrac{1 + 1}{2}$}$

$\text{x = $\dfrac{2}{2}$}$

$\text{x = 1}$

$\text{TH2: x - $\dfrac{1}{2}$ = -$\dfrac{1}{2}$}$

$\text{x = -$\dfrac{1}{2}$ + $\dfrac{1}{2}$}$

$\text{x = $\dfrac{-1 + 1}{2}$}$

$\text{x = $\dfrac{0}{2}$}$

$\text{x = 0}$

$\text{Vậy x ∈ {0; 1}}$

$\textit{Ha1zzz}$