Tìm x biết: a) 4/9 -2/3x = 1/3 b) (5/6x +3 )^2 =4

a) \(\frac{4}{9} - \frac{2}{3}x = \frac{1}{3}\)

\(\frac{2}{3}x = \frac{4}{9} - \frac{1}{3}\)

\(\frac{2}{3}x = \frac{1}{9}\)

\(x = \frac{1}{9}:\frac{2}{3} = \frac{1}{9}.\frac{3}{2}\)

\(x = \frac{1}{6}\)

Vậy \(x = \frac{1}{6}.\)

b) \[{\left( {\frac{5}{6}x + 3} \right)^2} = 4\].

Suy ra \(\frac{5}{6}x + 3 = 2\) hoặc \(\frac{5}{6}x + 3 = - 2\)

Trường hợp 1:

\(\frac{5}{6}x + 3 = 2\)

\(\frac{5}{6}x = 2 - 3 = - 1\)

\(x = \frac{{ - 6}}{5}\)

Vậy \(x \in \left\{ {\frac{{ - 6}}{5};\,\, - 6} \right\}.\)

Trường hợp 2:

\(\frac{5}{6}x + 3 = - 2\)

\(\frac{5}{6}x = - 2 - 3 = - 5\)

\(x = - 6\)