Đáp án:
Giải thích các bước giải:
a) $\cfrac{(x+\cfrac{1}{2})^3}{3}=-\cfrac{1}{81}\\\Leftrightarrow \cfrac{(2x+1)^3}{3}=-\cfrac{8}{81}\\\Leftrightarrow (2x+1)^3=-\cfrac{8}{27}\\\Leftrightarrow 2x+1=-\cfrac{2}{3}\\\Leftrightarrow 2x=-\cfrac{5}{3}\\\Leftrightarrow x=-\cfrac{5}{6}$
b) $\cfrac{x-2}{2}=\cfrac{8}{x-2}\\\Leftrightarrow (x-2)^2=16\\\Leftrightarrow x-2=\pm 4\\\Leftrightarrow x=2\pm 4\\\Leftrightarrow \left[\begin{array}{l}x=6\\x=-2\end{array}\right.$
