1.2. Tìm \(x,\) biết:

a) \(\frac{1}{4} - 2x = 5\).                       

b) \(\frac{1}{2}x - \frac{1}{3} = 25\% .\)

a) \(\frac{1}{4} - 2x = 5\)

\(2x = \frac{1}{4} - 5\)

\(2x = \frac{{ - 19}}{4}\)

\(x = \frac{{ - 19}}{4}:2\)

\(x = \frac{{ - 19}}{4} \cdot \frac{1}{2}\)

\(x = \frac{{ - 19}}{8}\).

Vậy \(x = \frac{{ - 19}}{8}\).

b) \(\frac{1}{2}x - \frac{1}{3} = 25\% \)

\(\frac{1}{2}x - \frac{1}{3} = \frac{{25}}{{100}}\)

\(\frac{1}{2}x = \frac{1}{4} + \frac{1}{3}\)

\(\frac{1}{2}x = \frac{7}{{12}}\)

\(x = \frac{7}{{12}}:\frac{1}{2}\)

\(x = \frac{7}{{12}} \cdot 2\)

\(x = \frac{7}{6}.\)

Vậy \(x = \frac{7}{6}.\)