a) |2x - 1| = (-4)²
⇔ |2x - 1| =16
⇔ \(\left[ \begin{array}{l}2x - 1= 16\\2x - 1=-16\end{array} \right.\)
⇔ \(\left[ \begin{array}{l}2x=17\\2x=-15\end{array} \right.\)
⇔ \(\left[ \begin{array}{l}x=\frac{17}{2}\\x=-\frac{15}{2}\end{array} \right.\)
Vậy x ∈ {$\frac{17}{2}$ ; - $\frac{15}{2}$ }
b) [- $\frac{5}{24}$ + 0,75 + $\frac{7}{12}$ ] : (-2)
= [- $\frac{5}{24}$ + $\frac{3}{4}$ + $\frac{7}{12}$ ] : (-2)
= [- $\frac{5}{24}$ + $\frac{18}{24}$ + $\frac{14}{24}$ ] : (-2)
= $\frac{-5 + 18 + 14}{24}$ : (-2)
= $\frac{27}{24}$ : (-2)
= $\frac{-9}{16}$
