Tìm x, biết: a) 4x + 0,25 = 2,5

a) \(4x + 0,25 = 2,5\)

\(4x = 2,5 - 0,25\)

\(4x = 2,25\)

\(x = 0,5625\)

Vậy \(x = 0,5625\).

b) \(\frac{1}{2}:\left( {0,5x - 1,5} \right) = \frac{1}{5} - \frac{7}{{20}}\)

\(\frac{1}{2}:\left( {0.5x - 1,5} \right) = \frac{{ - 3}}{{20}}\)

\(0,5x - 1,5 = \frac{1}{2}:\frac{{ - 3}}{{20}}\)

\(\frac{1}{2}x - \frac{3}{2} = \frac{{ - 10}}{3}\)

\(\frac{1}{2}x = \frac{{ - 10}}{3} + \frac{3}{2}\)

\(\frac{1}{2}x = \frac{{ - 11}}{6}\)

\(x = \frac{{ - 11}}{3}\)

Vậy \(x = \frac{{ - 11}}{3}\).