Tìm giá trị của x , biết: (a) − 7/3 x = − 21/18 ; (b) ( x − 1 ) ( 3 − 2 x ) + ( 2 x − 1 ) ( x + 3 ) = 4 .

a) \(\frac{{ - 7}}{{3x}} = \frac{{ - 21}}{{18}}\)

\(3x = \frac{{ - 7.18}}{{ - 21}}\)

\(3x = - 6\)

\(x = - 2\)

Vậy \(x = - 2\).

b) \[\left( {x - 1} \right)\left( {3 - 2x} \right) + \left( {2x - 1} \right)\left( {x + 3} \right) = 4\]

\(3x - 2{x^2} - 3 + 2x + 2{x^2} + 6x - x - 3 = 4\)

\[10x = 10\]

\(x = 1\).

Vậy \(x = 1\).