Tìm x , biết: (a) 2 − x/4 = x − 3/− 5 ; (b) x ( 2 x − 5 ) + ( 4 x^3 − 6 x^2 − 6 x ) : ( − 2 x ) = 19 .

a) \(\frac{{2 - x}}{4} = \frac{{x - 3}}{{ - 5}}\)

\( - 5.\left( {2 - x} \right) = 4\left( {x - 3} \right)\)

\( - 10 + 5x = 4x - 12\)

\(x = - 2\)

Vậy \(x = - 2\).

b) \(x\left( {2x - 5} \right) + \left( {4{x^3} - 6{x^2} - 6x} \right):\left( { - 2x} \right) = 19\)

\(2{x^2} - 5x + \left( { - 2{x^2} + 3x + 3} \right) = 19\)

\(2{x^2} - 5x - 2{x^2} + 3x + 3 = 19\)

\( - 2x = 16\)

\(x = - 8\)

Vậy \(x = - 8\).