a/ (2x - 1)³ = -8
(2x - 1)³ = -2³
⇒ 2x - 1 = -2
2x = -2 + 1 = -1
x = $\frac{-1}{2}$
b/ (x + $\frac{1}{2}$ )² = $\frac{1}{16}$
(x + $\frac{1}{2}$ )² = $($ $\frac{1}{4}$ $)$$^{2}$
⇒ x + $\frac{1}{2}$ = $\frac{1}{4}$ hay x + $\frac{1}{2}$ = $\frac{-1}{4}$
x = $\frac{1}{4}$ - $\frac{1}{2}$ hay x = $\frac{-1}{4}$ - $\frac{1}{2}$
x = $\frac{-1}{4}$ hay x = $\frac{-3}{4}$