a, \(\left(x-\frac{1}{2}\right)^3=\frac{1}{27}\)
<=> \(\left(x-\frac{1}{2}\right)^3=\left(\frac{1}{3}\right)^3\)
<=> \(x-\frac{1}{2}=\frac{1}{3}\)
<=> \(x=\frac{1}{3}+\frac{1}{2}=\frac{2}{6}+\frac{3}{6}=\frac{5}{6}\)
b) \(\left(x+\frac{1}{2}\right)^2=\frac{4}{25}\)
\(\Leftrightarrow\orbr{\begin{cases}x+\frac{1}{2}=\frac{-2}{5}\\x+\frac{1}{2}=\frac{2}{5}\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\frac{-2}{5}-\frac{1}{2}=\frac{-4}{10}-\frac{5}{10}=\frac{-9}{10}\\x=\frac{2}{5}-\frac{1}{2}=\frac{4}{10}-\frac{5}{10}=\frac{-1}{10}\end{cases}}}\)
