Tìm x, biết: (a) 2x(5−3x)+2x(3x−2)=3. (b) 3x(x+1)−3x(x+2)=−6.

a) \(2x\left( {5 - 3x} \right) + 2x\left( {3x - 2} \right) = 3\)

\(10x - 6{x^2} + 6{x^2} - 4x = 3\)

\(6x = 3\)

\(x = \frac{1}{2}\).

Vậy \(x = \frac{1}{2}\).

b) \(3x\left( {x + 1} \right) - 3x\left( {x + 2} \right) = - 6\)

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

\( - 3x = - 6\)

\(x = 2\).

Vậy \(x = 2\).